Biological Suggestions. Mimicry (Distant 1899)

 

THE ZOOLOGIST

 

 

No. 697.— July, 1899.

 

 

BIOLOGICAL SUGGESTIONS.
MIMICRY.

By W. L. Distant.

Part I.

 

"Evidence has three degrees of force: demonstration, probability, plausibility."—Matthew Arnold.
"The essence of originality is not that it be new."—Carlyle.
"Nature suffers nothing to remain in her kingdoms which cannot help itself."—Emerson.

 

If, as we have before suggested, our only clue to the original, or even primitive, colouration of animals is lost and buried in the records of the geological past, in which we find structure—scantily and often confined to typical portions—but of colour nothing,[1] a much larger field is open to the palaeontologist who seeks for the origin of that animal structure which is so often alike described under the terms of "protective resemblance" and "mimicry." Friends and foes of those theories too frequently—both for attack and defence—conceive the wonderful protective disguises in nature as having been evolved during the time of present natural conditions;[2] whereas we should think not of years but of geological epochs, for time is only an imaginary quantity, alike useful to the mathematician and historian, a result of expressing the term of our short lives. Thus we may seek to multiply the years of our fugitive existence into a product which shall represent the limits of an unknown past, whilst we can only imagine space by the equivalent of time.

We have already ventured some suggestions on the subject of assimilative colouration, and we now approach a different class of phenomena, where the resemblance is not of colour alone, but also frequently of structure, by which animals exhibit a close resemblance to some inanimate object, and to which the term "Protective Imitation of Particular Objects" has been aptly proposed by Mr. Wallace.[3] One of the most striking examples is found in the Orthopterous family Phasmidæ,[4] and in what are generally known as the "Walking-stick insects." To use the graphic and accurate description of Mr. Wallace:—"Some of these are a foot long, and as thick as one's finger, and their whole colouring, form, rugosity, and the arrangement of the head, legs, and antennæ, are such as to render them absolutely identical in appearance with dead sticks. They hang loosely about shrubs in the forest, and have the extraordinary habit of stretching out their legs unsymmetrically, so as to render the deception more complete."[5] Mr. Wallace travelled both in the western and eastern tropics. The late Prof. Drummond records similar impressions in Africa:—"On finding one of these insects, I have often cut a small branch from an adjoining tree, and laid the two side by side for comparison; and when both are partly concealed by the hands so as to show only the part of the insect's body which is free from limbs, it is impossible to tell the one from the other. The very joints of the legs in these forms are knobbed to represent nodes, and the characteristic attitudes of the insects are all such as to sustain the deception."[6] Every writer, in fact, who approaches the subject of animal disguises, whether evolutionist or not, quotes these insects as one of the strongest illustrations he can find, and with ample warrant, for we may take these "Stick-insects" as affording a typical instance of what is understood as protective resemblance. The protection, however, cannot be complete, for Wallace found the stomachs of certain Cuckoos full of them.[7]

Now, it is a general postulate that this highly imitative and protected form is due to the action of "natural selection," acting on some incipient and original element of variation. As Mr. Bates observed:—"Natural selection having, from the first, favoured the species which offered variation in these parts, the tendency to variability has become perpetuated by inheritance."[8] Or, as Mr. Darwin put it:—"Assuming that an insect originally happened to resemble in some degree a dead twig or a decayed leaf, and that it varied slightly in many ways, then all the variations which rendered the insect at all more like any such object, and thus favoured its escape, would be preserved, whilst other variations would be neglected and ultimately lost; or, if they rendered the insect at all less like the imitated object, they would be eliminated."[9] We should therefore expect, if a perfect geological record could unfold the ancestry of these insects, to trace a gradual evolution of form for protective purposes under the influence of natural selection. Such an investigation has been attempted, and such a result apparently obtained by Mr. Cameron, in his search for "the origin and purpose of the horns and antlers of ruminants." He concludes "that the horns and antlers of ruminants are the result of a defensive adjustment in biological answer to carnivorous teeth and claws, and consequent upon the relations of destroyer and destroyed which obtained between carnivores and ungulates throughout Tertiary time.... Their historical appearance in the Miocene age of the Tertiary period is contemporaneous with a vast extinction of hornless ungulate families, and their subsequent development in an ascending scale corresponds with the gradual thinning out of unarmed ungulate genera, and the gradually increasing destructive pressure upon those, whether armed or unarmed, that survived. Their evident loss of calibre since palæolithic times may be traced chiefly to the coming of man with missile weapons, which, in altering the character of the destroying agency, discounted the value of cranial armature in the struggle for life."[10]

It is a remarkable fact with these Phasmidæ that giant forms are said to have existed even in the Carboniferous fauna. Among other Orthoptera belonging to that era were "the giant Walking-sticks recently brought to light from the coal-measures of France, the Titanophasma fayoli, which measure in length (in one specimen) upwards of twelve inches, and are therefore, by linear measure, very nearly the largest of recent as well as fossil insects."[11] It is necessary, however, to observe that much caution must be exercised in the identification of these fossil remains. Dr. Sharp is at least sceptical, for he writes:—"In the Carboniferous layers of the Palæzoic epoch there are found remains of gigantic insects that may possibly be connected with our living Phasmidæ."[12] The same writer, however, has subsequently given a less undecided opinion: "Phasmidæ are insects of extreme interest; they appear to be the nearest living representatives of an insect fauna that was predominant in the Carboniferous epoch."[13] Brongniart and Scudder have proposed a distinct family—Protophasmidæ—for these fossil remains, though Scudder's "restoration" of T. fayoli is perhaps, and necessarily, somewhat imaginary. Mr. Comstock maintains that "we must turn to the Carboniferous as the earliest epoch from which we have data to base our conclusions regarding the structure of the primitive insect wings";[14] whilst Huxley believed that "the Carboniferous Insecta and Arachnida are neither less specialized, nor more embryonic, than those that now live."[15]

If, however, we suppose, as we may reasonably do, that these Carboniferous Phasmidæ must have been protected forms of insect life at that period—for it is by their peculiar structure that the fossil remains are recognized—the imitative resemblance would also have a different meaning and a diverse reference to what now obtains. Respecting fossil Cockroaches, Mr. Scudder states:—"The first Cockroach wing ever described was first described as a fern leaf, and in all, or nearly all, the localities where their remains have been found they are associated with fern leaves in immense abundance. While searching for their remains in the Permian deposits at Carsville, I was much struck by this resemblance, and was repeatedly obliged to use the glass to determine whether it was the wing of a Cockroach or the frond of a fern I had uncovered, and the instances are not rare where they agree completely in size. The general distribution of the nervures is to cursory view the same in each, and the form is often nearly identical."[16] The flora of the Carboniferous era was very different to that of the present epoch. The mighty forests of gigantic horse-tails, club-mosses, and tree-ferns replaced or anticipated the jungles and woods of to-day; and, as Haeckel truly observes:—"It is difficult for us to form any idea of the very peculiar nature of those gloomy palæolithic fern-forests, in which the whole of the gay abundance of flowers of our present flora was entirely wanting, and which were not enlivened by any bird or mammal."[17] Prof. Geikie describes it as "marked by a singular monotony of character all over the world from the Equator into the Arctic Circle, the same genera, and sometimes even the same species, appearing to have ranged over the whole surface of the globe. It consisted almost entirely of vascular cryptogams, and pre-eminently of Equisetaceæ, Lycopodiaceæ, and Ferns. Though referable to existing groups, the plants presented many remarkable differences from their living representatives. In particular, save in the case of the ferns, they much exceeded in size any forms of the present vegetable world to which they can be assimilated. Our modern horse-tails had their allies in huge trees among the Carboniferous jungles, and the familiar club-moss of our hills, now a low-creeping plant, was represented by tall-stemmed Lepidodendra that rose fifty feet or more into the air. The ferns, however, present no such contrast to forms still living. On the contrary, they often recall modern genera, which they resemble not merely in general aspect, but even in their circinnate vernation and fructification. With the exception of a few tree-ferns, they seem to have been all low-growing plants, and perhaps were to some extent epiphytic upon the larger vegetation of the lagoons."[18] Now, if we keep in mind this description of the very different flora that then existed, we cannot help recognizing the fact that these Stick-insects would either have a totally different relation to the trunks of those tree-ferns to what they bear to the branches and twigs of trees as known to ourselves, or that they then—as is more probable—by a difference of form to their present descendants, assimilated to their then environment.

Again, the more ancient existence of the Phasmidæ, prior to the Carboniferous epoch, is implied, for it is impossible to imagine on any evolutionary principle that these giant insects came suddenly into existence at that era, especially if, as we believe, their imitative structure is due to the action of natural selection. In that case there must have been antecedently less specialized forms, less imitative structure. "Considering the abundance of Walking-sticks in Paleozoic rocks, the absence of their remains from Mesozoic strata is rather remarkable."[19] But the difficulties in the clear conception of this question do not end here. As early as this Carboniferous epoch, these insects appear to have possessed what we naturally consider as a protected or imitative structure, and this view is inconceivable without the antecedent proposition that their enemies then existed, and that the imitative guise was that of the oft-devoured against the would-be-devourer. But it is affirmed that Lizards do not appear before the Permian epoch,[20] birds as certainly not before the Jurassic[21] or perhaps the Triassic formation. "It is quite possible that birds existed during the Triassic period, but at present there is no proof of it."[22] And if these facts were taken as final, then an insuperable difficulty would exist as to the structure of these Phasmidæ being due to a gradually acquired protective character. But the same argument applies to these ancient Lizards as to our Carboniferous Stick-insects. As Huxley remarks, "These Permian Lizards differ astonishingly little from the Lizards which exist at the present day"; and again, "It is perfectly clear that if our palæontological collections are to be taken, even approximately, as an adequate representation of all the forms of animals that have ever lived, and if the record furnished by the known series of beds of stratified rocks covers the whole series of events which constitute the history of life on the globe, such a fact as this directly contravenes the hypothesis of evolution; because this hypothesis postulates that the existence of every form must have been preceded by that of some other form different from it."[23] If we study the records of animals that have lived at a former period of the world's history, but have at present no representatives, we shall find,—to again quote our previous authority, "Among the Mammalia and birds there are none (orders) extinct; but when we come to the reptiles there is a most wonderful thing: out of the eight orders or thereabouts which you can make among reptiles one-half are extinct."[24] Amphibia, however, certainly existed, and were apparently abundant in the Carboniferous age; and, as Mr. Thomson remarks, "the food of adult amphibians usually consists of insects, slugs, and worms."[25] We may surmise that many were arboreal in their habits, and these, before the advent of the true reptiles and birds, must have constituted the principal insect enemies. We must also recollect that the Pterodactyles, or Flying Dragons, during the long reptilian period, "played the rôle of the bats and birds of the present day."[26] The imperfection of the geological record is, however, no argument against evolution, though it seems strange it has not even been made of much more use by some opponents. The struggle for life is an ancient one, but the combatants have not always been the same. In Pliocene times, as Prof. Owen has stated, "Bats, Moles, and Shrews were then, as now, the forms that preyed upon the insect world in this island."[27] The number of mammals which devour insects seem sometimes overlooked, and this fact can be easily realized by looking through the pages of any good treatise on the Mammalia, and tabulating the nature of the food used by the different animals. For the purpose of the present discussion it should be remembered, as remarked by Mr. W.L. Sclater, that the conclusion is more than probable "that before the commencement of the Tertiary epoch the whole world was, so far as is at present known, inhabited by small insignificant mammals distinctly allied to the marsupials."[28]

Perhaps one of the inevitable faiths is that of the man of science who neither disguises the necessity of the halt, nor disbelieves in the certainty of the forward march, and these Carboniferous Phasmidæ almost prove the pre-existence of the Permian reptiles and the Jurassic birds.[29] If these stick-insects really possessed, and did not derive their imitative structure for protective purposes, then the whole theory of "Protective Resemblance" among insects may go to the wall. The need of protection must undoubtedly have existed in Carboniferous times, if this hypothesis is to stand, and such a view helps to prove, as Huxley has already urged, a pre-Permian existence for reptiles,[30] and, we may add, a greater antiquity also for birds, both of which, we may presume, were, as now, great enemies to insect-life.

The only other explanation—known to the writer—which has been offered to account for the peculiar structure of these Stick-insects, is one proposed by the late Prof. Karl Semper, which would have received additional emphasis had that naturalist been aware (he at least does not allude to the fact) of the Phasma being found as a Carboniferous fossil. Prof. Semper's proposition is that the structure denotes what has been styled "'Larva-forms,' a name given to all animals which possess the characters of the larvæ of other species, and are nevertheless capable of sexual reproduction." The opinion is amplified by the following explanatory illustration:—"Thus species of the same genera, perhaps even the very same species, in our damp and cold climate, do not produce a new generation till they are fully grown; while in the dry warm region of the Mediterranean they have produced two generations before they are fully grown."[31] This would be somewhat on a line with the suggestion we have made that most unicolorous animals are survivals from an original assimilative colouration, and have thus survived by being in harmony with their surroundings, and thus coming under the sanction and perpetuating influence of natural selection. On this theory the Stick-insect would be merely the survival of an ancient "Larva-form" which fulfilled the same purpose, and thus also came down to us unchanged under the fostering care of the same selective influence. But Prof. Semper, further speculating on the fact of these insects comprising winged and wingless forms, is inclined to account for the same by the "optimum temperature"[32] under which the eggs have been matured. A fuller knowledge of these Phasmidæ will scarcely support this proposition. What we find is a most graduated and complicated connection between the winged and wingless forms. The late Prof. Westwood, a most determined opponent to evolution in any shape or form, contributed—as so many other opponents have done before and since—unconscious testimony to the same, in an artificial classification which he proposed for the family.[33] As summarized by Mr. Bates:—"The groundwork of this classification is the gradation or development of the wings from genus to genus. Thus it begins with those genera which are wingless in both sexes, these forming one Division, and passes through those in which the males are winged and the females wingless, or in which the wings are rudimentary, to the genera which have well-formed wings in both sexes—the whole of the latter forming the second Division. The wingless series commences with those forms which have much abbreviated antennæ and very attenuated bodies, and progresses to those having long setiform antennæ, or bodies of much more compact structure. The winged series progresses gradually from those genera in which the upper and lower wings are either rudimentary, or developed in one sex only, to those in which they exist in both sexes (but the upper wings of extreme shortness), ending at length with genera in which both upper and lower wings have become elongated in an approach to due proportion."[34] This complicated classification, which expresses the difficulties and intricacies of evolution in every sentence, naturally sometimes fails in the details of its own arrangement, but is sufficient to throw more than grave doubts on the explanation offered by Prof. Semper. The consideration of the present knowledge applicable to these Phasmidæ appears to warrant the following conclusions:—

1. The Walking-stick insects are usually considered by naturalists to be undoubted examples of "Protective Resemblance," due to a process of "Natural Selection."

2. If they are found with a somewhat similar structure in the Carboniferous fauna, they must therefore be the result of a previous course of evolution.[35]

3. Reptiles and birds, well-known insect enemies, are generally considered as posterior to the Carboniferous epoch.

4. But as the Permian reptiles were fully developed as we know them now, they must have had an earlier and less differentiated structure; the same suggestion being applicable to the Jurassic birds.

5. The presence of the imitative Phasmidæ in the Carboniferous epoch implies the existence of enemies, probably reptiles, and possibly a transitional form of bird-life.

Good cause is shown why we should seek in past geological epochs for the earliest traces of protective resemblances and mimicry, for the absence of observed attack in the present time does not disprove a great danger and want of protection in the dim eras of the past. "In studying protective resemblance and mimicry among living animals, the exceedingly common occurrence of these phenomena has often forced upon me the conclusion that they have not been limited in their scope to recent times, but must have existed in past epochs, and even, to some extent at least, in very remote epochs."[36] When gadflies are about, the Ox "seems to be seized with an unreasoning paroxysm of fear." "In modern times the gadfly merely causes some fear and a little discomfort to an animal, and some loss of money and temper to its owner when he finds that the hide has been perforated, and is therefore held cheap by the tanner. But there must have been occasions when the war between gadflies and cattle was a much more serious affair. So strongly marked a protective instinct can only have been produced at a time when the very existence of the species was threatened by parasites of this order."[37] Sir Charles Lyell, as early as 1836, and before much had been thought or expressed on the subject—for Darwin had not then returned from his epoch-making voyage—appears to have had clear conception of the phenomena, though based on very different philosophical views to those he embraced and enunciated later on. In a letter to Sir John Herschel, he advances probable causes that may aid a species' duration in time. "Now, if it be an insect, it may be made in one of its transformations to resemble a dead stick, or a lichen, or a stone, so as to be less easily found by its enemies; or, if this would make it too strong, an occasional variety of the species may have this advantage conferred upon it; or, if this would be still too much, one sex of a certain variety. Probably there is scarcely a dash of colour on the wing or body of which the choice would be quite arbitrary, or what might not affect its duration for thousands of years. I have been told that the leaf-like expansions of the abdomen and thighs of a certain Brazilian Mantis turn from green to yellow as autumn advances, together with the leaves of the plants among which it seeks for its prey. Now, if species come in succession, such contrivances must sometimes be made, and such relations predetermined between species, as the Mantis, for example, and plants not then existing, but which it was foreseen would exist together with some particular climate at a given time."[38]

If we were referring to insects in general, and not to these Phasmidæ in particular, we should not lay such stress on the probability of their enemies in the past being largely reptiles[39] and birds. No one who has collected insects beneath an electric light, as I have frequently done at Pretoria, attended in the same pursuit with the shadowy rushes of Bats above, and a host of patient Batrachians beneath, can doubt what wholesale insect destroyers are found in the ranks of the Chiroptera and Amphibia. But although I have found all orders of insects attracted by these lights, including Orthoptera—comprising Mantidæ, Achetidæ, Forficulidæ, Blattidæ, Gryllidæ, and Locustidæ—I personally never met with any representatives of the Phasmidæ, though of course these insects may also prove to be nocturnal in their habits, and to be also attacked by Bats. But as these animals have not been traced further back than Eocene times, we can scarcely regard them as having proved enemies to the Carboniferous Stick-insects. With the Amphibia the case is different, and, according to the late Prof. Martin Duncan, "the most ancient Amphibia appear to have first lived during the Carboniferous age, and all were tailed, had pleurodent teeth, simple in their construction.... Some were Lizard-like and others were serpentiform.... They are the Microsauria (Dawson), and the genera Hylerpeton (Owen), Hylonomus (Dawson), Brachydices (Cope), and Ophiderpeton (Huxley) are typical."[40] Here we have a host of contemporary Carboniferous enemies who may indeed have proved a great trial to the existence of unprotected Phasmidæ, and who may synchronously with the evolution of themselves have indirectly caused or induced a protective evolution in the structural form of these insects, by the mutual interdependence in those relations of cause and effect which can be expressed by the well-known appellation "natural selection." And so, for the sake of the argument, dismissing even the agency of either reptiles or birds, we still have abundant reason for believing that, though the protective resemblance of these Phasmidæ was already acquired in Carboniferous times, the presence of Amphibia in an evolutionary sense is quite sufficient to account for it. This prompts two reflections: one that we ought to look a long way back for the origins of these protective and mimetic guises; and the other, that we may reasonably hope to find them. The present attitude of many champions of the cause, who seek to find, or to invent, present factors for producing these phenomena, seems fraught with peril for the whole theory; and with the same weariness and perseverance with which the original promulgators thought out the doctrine, we must go on searching for further proofs, which will necessitate our appealing to the Cæsar of the past—the ever-growing science of palaeontology.[41] In this domain many similar problems still remain unsolved. In the old red sandstone of Scotland are abundant remains of fishes, such as Osteolepis, but the reason why these and so many other ancient creatures were enveloped or armed in coats of mail, or rather the antecedent factors provocative of the evolution, has not yet been discovered.

In taking leave of these protected Phasmidæ we will record two—and only two—testimonies to their imitative deception, one old and the other modern.

When Pigafetta visited the island of Palawan, he saw many wonders, and described one as follows. There "are found certain trees, the leaves of which when they fall are animated and walk. They are like the leaves of the mulberry tree, but not so long; they have the leaf-stalk short and pointed, and near the leaf-stalk they have on each side two feet. If they are touched they escape, but if crushed they do not give out blood. I kept one for nine days in a box. When I opened it, the leaf went round the box."[42] This may be taken as a strong, and, what is more, then unsolicitated, testimony to the efficacy of protective resemblance among insects. Linnæus, doubtless with the true inwardness in his mind, wrote:—"Anyone who happens to see, in the Indian woods, the falling leaves of trees apparently become alive, and creep upon the ground."[43]

Our second illustration is from the pen of that keen and excellent observer, Mr. Belt:—"I was much surprised with the behaviour of a green leaf-like Locust. This insect stood immovably among a host of Ants, many of which ran over its legs without ever discovering there was food within their reach. So fixed was its instinctive knowledge that its safety depended on its immovability, that it allowed me to pick it up and replace it among the Ants without making a single effort to escape. This species closely resembles a green leaf."[44]

 

If we consider it unsafe to predicate the colours of animals in past geological eras on the basis of their present hues and markings, it is as equally unwarranted to conclude that the nature of their food was the same then as now. And therefore we must be prepared to admit that probably insects had enemies in the past which are now only known as non-insectivorous, and the same suggestion will apply to other animals. This line of argument is prompted by the many recorded examples of wild and domesticated animals who have taken to a food totally different to that of other members of their family and even genus. It is necessary to give some examples, for, if not overlooked, such facts seem little taken into consideration. At the same time only some among many instances can be quoted.

Mammals.Macacus cynomolgus, a well-known Monkey of Malasia, according to Sir Arthur Phayre, frequents salt water creeks and devours shell-fish, thus being known among naturalists as "the Crab-eating Macaque." "A l'égard des jeunes oiseaux, le gorille et le chimpanzé font preuve d'une telle voracité qu'ils avalent leur proie sans la déplumer."[45] Bonvalot narrates that small Thibetan Horses "feed on raw flesh, as we have seen with our own eyes."[46] Sandeman, writing of South Africa, observes that, though many of the Horses never get over their dislike to the smell of blood, he possessed one that rather liked it, and found him one day "licking the bleeding carcass of a newly-skinned Bôk."[47] It has been stated that "African Horses very commonly eat their own dung; and numbers have been destroyed in consequence of taking into the stomach vast quantities of flinty sand."[48] Dr. Stockwell, writing from Ontario, Canada, states:—"At certain points on the shores of Lake Huron the soil is quite sterile,—that is, very sandy,—and those who attempt to cultivate frequently use as compost fish caught in seines from the lake. These fish are chiefly Suckers (Catastomidæ), Dog-fish (Amiidæ), Herrings and Lesser Mackinaw Trout (Coregonus artedi, Le Sueur, and Salvelinus, both of the Salmonidæ). Frequently the maize which is planted in hills along with fish fails to exhibit a vigorous growth when cattle are turned in to graze them." But not only the cattle are attracted by the fish. "Some twenty years since a gentleman in the States imported a herd of a hundred and eighty Horses from the Shetlands, and was obliged to keep them for some time close to tide water, where they could get salt sedge grass and a diet of fish, such as they had been accustomed to. Gradually they were weaned to feed upon hay and grain. I have repeatedly seen Horses from this herd, or their descendants, if offered a piece of raw fish devour it with the greatest gusto."[49] Other animals embrace a fish diet with avidity. In Kamschatka during the long winters, when it is difficult to procure food of any kind, there is a consequent necessity of fish as an article of diet for almost every living creature in the settlements—"the Cows and Horses even not excepted."[50] In the same country when the streams are surcharged with fish, the Bears "live entirely upon Salmon. Later, when this diet fails them, they take to berries, upon which they live until the time of hybernation."[51] "There are indeed but few animals, apparently, which do not live on Salmon in Kamschatka."[52] Gilbert White has remarked "on the violent fondness for fish" possessed by common house Cats, when, "of all quadrupeds, Cats are the least disposed towards water, and will not, when they can avoid it, deign to wet a foot, much less to plunge into that element."[53] To this Mr. Harting adds a note:—"It is generally supposed that Otters live exclusively on fish, but such is not invariably the case. They are carnivorous as well as piscivorous, and have been known to eat Ducks and Teal, and, while in confinement, young Pigeons. Frogs form part of their bill of fare, and even Mussels at times furnish food to these animals."[54] The Common Armadillo (Dasypus villosus) is an adroit capturer of Mice, and Mr. Hudson "frequently found their stomachs stuffed with clover, and, stranger still, with the large hard grains of the maize swallowed entire."[55] "The Zoo Otters have conformed to the universal tendency to extend the range of diet by eating shipbiscuit as well as fish."[56] According to Mr. Lydekker, Otters have been known when hard pressed during winter to make occasional raids on the farmyard, where they have been asserted not only to kill poultry, but also young Lambs and Pigs.[57] As stated by Mr. Dimmock, "Adolph Müller mentions that his Cat regularly hunted at twilight the moths, chiefly Noctuidæ, in his garden" ('Zool. Garten,' Aug. 1880, jahr. 21, pp. 253–4). He also states, from his own experience: "About 1870 I had a Cat that nearly every hot afternoon in summer and autumn caught Grasshoppers (Caloptenus and Œdipoda), and brought me her insect captures alive before eating them, with as much pride as if she had taken Mice or birds." He also noticed "several Cats capture and eat beetles of the genera Lachnosterna and Prionus; the odour of the beetles of the latter genus seems sufficiently pungent and repulsive to drive away Cats, since they dislike most pungent odours; but I have seen two Cats that apparently regarded Prionus as a delicacy, for they would eat dead, mutilated, sometimes half-decayed beetles of this genus which they found about the yard."[58] Of the North American Mustela vison Darwin relates, "During the summer this animal dives for and preys on fish, but during the long winter it leaves the frozen waters, and preys, like other Polecats, on Mice and land animals."[59] The Bactrian Camel (Camelus bactrianus), instead of confining itself to a strictly vegetable diet, will, according to Prejevalski, when pressed by hunger, readily devour almost anything that it may come across, including felt blankets, bones and skins of animals, flesh, and fish.[60] That prolific pest in Australia—the Rabbit—is now said to have learned to live and thrive on bark and the twigs of bushes, and even to have developed the power of getting up trees[61] in search of food, going up as high as eight feet, using their teeth to climb with.[62] When the Hamsters (Cricetus frumentarius) issue in the spring from the burrows in which they have have passed their winter hybernation, "they devour ravenously almost anything that comes before them, not refusing an occasional young bird, a mouse, or a beetle."[63] As is generally known, the usual food of these animals is of a vegetable nature. "Reindeer devour hundreds and thousands of Lemmings."[64] Mr. J.A. Thomson states that he had a report on creditable authority that in the hard winter 1894-95, Stags in Aberdeenshire were known to have eaten Rabbits."[65] The Chacma Baboon in some parts of the Cape Colony "has largely taken to killing Lambs for the purpose chiefly of sucking the milk with which they have filled their stomachs."[66] In Egypt, Hyænas are "said to feed on Indian corn, and be destructive to the crops."[67] In the Scottish Highlands, near the head of Loch Garry, Foxes were strictly preserved and plentiful. A year or two ago, when their cubs were ravenous, these Foxes took to killing Lambs in the fields around, and the unusual spectacle in Britain "was seen of large fires kept burning all night to scare them away, while slumber was driven away from the eyelids of those who lived near by the incessant blowing of tin trumpets and firing of guns charged with powder only."[68]

Birds.—Ostriches, according to Mr. Cronwright Schreiner, have been known to swallow oranges, peaches, small Tortoises, Fowl and Turkey chickens, and kittens.[69] The Spreo (Spreo bicolor) "was formerly never known to touch fruit, its food consisting entirely of insects; but during recent years it has, at all events on some farms with which I am acquainted, become very destructive to fruit."[70] Dr. A.G. Butler, who has much experience in aviculture, states that he has "seen the American Bluebird, the English Starling, the Robin, Redstart, and many other insectivorous birds swallow quantities of seed, and benefit greatly in consequence."[71] "It is within the memory of some still living that the Rooks first commenced to eat turnips about fifty years ago."[72] Perhaps the most remarkable case is found in the New Zealand Kea or Parrot (Nestor notabilis), which has recently developed a taste for a carnivorous diet. As described by Mr. Wallace: "It began by picking the sheep-skins hung out to dry or the meat in process of being cured. About 1868 it was first observed to attack living sheep, which had frequently been found with raw and bleeding wounds on their backs. Since then it is stated that the bird actually burrows into the living Sheep, eating its way down to the kidneys, which form its special delicacy."[73] The absolute accuracy of this explanation of the bird's intentions, has been denied by Messrs. Taylor White and Huddelston, both New Zealand authorities. According to these writers, "the bird settles on the sheep above the kidneys because it is the broadest part, and it can there obtain the best grip of the wool; and Mr. White considers that blood rather than flesh is what the bird desires.[74] On the island of Porto Santo, near Madeira, the stomach of a Kestrel was found to contain "nothing but seven Snail shells (Helix pisana), which had been swallowed whole."[75] As Darwin enquires, "Can a more striking instance of adaptation be given than that of a Woodpecker for climbing trees and seizing insects in the chinks of the bark? Yet in North America there are Woodpeckers which feed largely on fruit, and others with elongated wings which chase insects on the wing."[76] The Great Titmouse (Parus major), by its larger size and stronger bill, is adapted to feed on larger insects, and is even said sometimes to kill small and weak birds. The smaller and weaker Coal Titmouse (Parus ater) has adopted a more vegetarian diet, eating seeds as well as insects, and feeding on the ground as well as among trees.[77] It has been stated that "on Cocos Islands, when the Boobies are not nesting and have consequently left, the Frigate birds (Tachypetes aquila) are unable to procure their ordinary food, which consists of fish taken from the Boobies, and that they then swallow seeds of Guilandina and beans, which they find floating in the sea, and on flying to the land vomit them up again, apparently merely using them to fill up temporarily the empty crops."[78] Mr. Watson, in describing the effects of illegitimate fishing in our own country, writes, "In one outlying village during last close season poached Salmon was so common that the cottagers fed their poultry upon it right through the winter."[79] "After Hunter had fed a Sea Gull on grain for a year, he found that the inner coat of its stomach had grown hard, and its muscles had thickened, thus forming a true gizzard, although the Sea Gull normally has a soft stomach, as it lives upon the soft flesh of fishes."[80]

Dr. Vosseler, in making some experiments on young Salamanders (Salamandra maculata), inadvertently left some in an aquarium for over a year unfed. "Investigations showed that these creatures, which usually fed on worms, all kinds of larvæ, &c, had nourished themselves with Algæ together with Infusoria. They had thus become almost complete vegetarians."[81]

Insects.—Numerous instances will occur to most entomologists, and are to be found scattered in entomological literature. We will again quote from other writers: "Many caterpillars, though plants are their proper food, will occasionally exhibit depravity of taste, and if kept with their own kind or with the larvæ of other moths, may turn cannibal, and make away with the company. Similarly the large green Grasshopper will eat insects smaller than itself, as well as its ordinary vegetable diet."[82] The household beetle pest Dermestes, whose larvæ not only prey on flitches of bacon, meat in larders, bladders covering jam-pots, and even books and papers, "have sometimes actually imitated the example of Anobium, and bored into wood, feeding on the timber as they advanced."[83] In various places, such as parts of India, for example, Mosquitos are found in swarms in spots never visited by human beings, and in which there are no large mammals. It has been suggested that, failing to obtain blood, Mosquitos support themselves on the juices of plants, but no observations in support of this have been recorded.[84] Even the sexes in some insects are totally diverse in the nature of their food. In the Diptera, of the families Culicidæ and Tabanidæ, according to Prof. Westwood, "it is only the females of these insects which are blood-suckers, the males being found on flowers; and Meigen discovered that the mouth of the latter sex is destitute of mandibles."[85]

Mankind.—Even man can acquire a partiality for salt or brackish water. Barrow relates that an old man in the Bokkeveld of South Africa, "who from his infancy till a few years past had lived in Zwartland, never missed an opportunity of sending thither a few bottles to be filled with the briny water for his own particular use; the pure stream of the mountain, as he asserted, not being able to quench his thirst."[86] The South Australians first learnt from Europeans to eat Oysters.[87] The Australians do not, however, eat everything indiscriminately, but reject several things eaten by Europeans, as certain fish, crustaceans, or fungi; yet they feel no disgust at such things as maggots or rotten eggs, or even the contents of the intestines of animals taken in hunting.[88]

Plants can also vary the nutrient salts they absorb according to the supply of the same. In the yew (Taxus baccata) there is frequently a replacement of calcium by magnesium. On comparing the quantities of calcium and magnesium in the ash of yews grown on lime and on gneiss, respectively, with those yielded in the case of serpentine formation, we find that magnesia preponderates considerably in weight over lime in a yew from serpentine rocks (which are in the main a compound of magnesia and silicic acid), whilst the proportion between these two salts is reversed in a yew grown upon limestone. The obvious inference from the table is that, in plants from a serpentine ground, lime is to a great extent replaced by magnesia.[89]

Among other vagaries in animal diet may be mentioned that of Snails, who also devour insects, particularly Coleoptera.[90] On the other hand, the operation is sometimes reversed. M. Flaminio Baudi found Cychrus cyclindricollis feeding on the body of Helix frigida;[91] and Mr. Trovey Blackmore had observed Carabus stenocephalus to feed on the abundant Snails in Morocco.

Such facts as these tend to prove that a fauna is not happy by having no history, as is so often and so easily imagined; but rather that its history is like that of a continental humanity—one series of wars, attack not on all sides at once, but ever recurring from one quarter or another. The friend of to-day may have been the enemy of a long ago. Environmental changes may have produced, by a scarcity of usual food, a change of diet, and then a race of animals hitherto enjoying a comparative immunity from attack may suddenly become almost annihilated by unexpected foes. Thus we may now find an inherited mimetic resemblance among insects and other living creatures which we seek in vain to explain by observed attack, and consequently cannot prove the present need of protection. These disguises are often like remains of old earthworks which we find on our peaceful downs; reminiscences of past struggles, records that such did once exist. And thus the suggestion is forced upon us that much present mimicry in nature is obsolete, more to be studied and explained by a zoological archæologist than by an outdoor observer, and accounts for the frequent remarks made from time to time to the writer by candid and competent naturalists abroad, that so much convincing theory at home receives little support when nature is cross-examined in her tropical and sub-tropical fastnesses.

 

In a book written by a popular writer, the late Prof. Henry Drummond, and which must have been read largely by the general public, for before us is the fourth edition of 'Tropical Africa,' which is described as "completing twenty-fifth thousand," there is a chapter devoted to "Mimicry; the ways of African insects."[92] "Protective resemblance" would perhaps have been a more applicable title to the phenomena considered than "mimicry,"[93] which the author defines as "imposture in nature." But the peculiarity in this chapter is that the author, after agreeing in the fullest manner with the usual conception of the term "mimicry," as held by most biologists, and stating that "mimicry depends on resemblances between an animal and some other object in its environment of which it is a practical gain to the creature to be a more or less accurate copy,"[94] appears to altogether explain away that conclusion by the subsequent remark that, "while in some animals the disguises tend to become more and more perfect, the faculties for penetrating them in other animals must continually increase in subtlety and power."[95] This argument, if it could be substantiated, appears to be, and has always impressed the writer, as one of the most complete answers to the whole theory of the protective meaning of these disguises. For if by the slow process of adaptation all variations tending to these disguises were increased and perpetuated by the process we express as "natural selection," thus ever helping the "survival of the fittest," and at the same time these changes or developments were equally studied and more keenly detected by the attentive and hungry host of insect enemies, the relations between the attackers and the attacked, the eaters and the eaten, would remain much the same at the commencement and end of the process. And therefore what becomes of Prof. Drummond's conception of mimicry, with its "practical gain," if the enemies sought, or supposed to be deceived thereby have their penetrating faculties continually increasing in subtlety and power? A moth, Agrotis cursoria, not uncommon to the sand-hills on the coast of our own country, "hides in the daytime in dense tufts of Ammophila arundinacea (Marram grass) close to the surface of the sand, and among other plants on the sea sand-hills." But "its partiality for this shelter is apparently well known to the birds, as is testified by the numbers of detached wings to be seen lying about."[96] Mr. Rodway gives a similar experience in the Guiana Forest:—"Invisibility is a striking characteristic of every living thing in the forest. At first a stranger observes nothing but a scene of desolate confusion. Later, however, he begins to distinguish one tree from another, and learns where to look for a particular animal. Then he wonders how he could have missed the signs which now impress themselves upon his eyes."[97] It is similar to the extra thickness in the armour of the ironclad, which is always influencing the construction of guns possessing greater penetrating power. It is like the acquired aptitude of the village bird-nesting boy, who with difficulty succeeds in making the town lad see the concealed nest he is about to take; or the experienced eye of the angler which recognizes the Trout, undetected by the ordinary walker on the bank. Or again, watch the rambles of the out-door collector and the closet-naturalist; or the entomologist who discovers and captures, and the other entomologist who only classifies and describes. It is the old remark of "Eyes" and "No Eyes."[98] If then we can for the purpose of sport or science pit our discerning faculties against the extreme power of animal disguises,[99] how much more must that detective discrimination have been acquired by those creatures whose very lives are so largely passed in the search, and depend on the capture of these mimicking fugitives. Even the obscure Coccids are preyed upon by birds. Mr. Newstead found specimens in the stomach of the Blue Tit (Parus cæruleus), and remarks:—"These birds must have keen eyes to distinguish this species, for it is well protected both in colour and texture. The central red-brown speck in the scale is the only indication of its presence, and altogether it may be considered the best protected of any of our British Coccidæ."[100] Again, birds learn to recognise hurtful as well as advantageous objects as exemplified by telegraph wires. When these were first elevated they caused great mortality among birds which flew against them, but after a time the wires were avoided, and that loss in avian life was vastly reduced. Birds certainly acquire experience and avoid dangerous food. Frank Buckland relates that a keeper at Castle Forbes poisoned dead Rabbits, and "picked up as many as twenty-one Magpies and Crows to one Rabbit at one time." But "the cunning birds found out that it was dangerous to peck at dead Rabbits, in vain therefore were they laid down; the Crows and Magpies were for a season triumphant. But the keeper substituted Wood Pigeons for Rabbits, and the 'vermin birds' once more fell victims."[101] It is not related how long this bait sufficed. Eimer relates that, requiring Sparrows for the zootomical studies of his students, he procured a new and ingeniously constructed trap. "The result of the use of my trap was surprising; almost immediately quite a dozen Sparrows were caught in it. These were brought away as carefully as possible, so that none were taken out in sight of their companions. The trap was again set, and this time nine Sparrows were caught equally quickly. I was very pleased with the invention, for it seemed likely to put an end for the future to all my difficulties. But it was to be otherwise. I noticed already that all the Sparrows caught were young birds, hatched the same spring, and therefore of little experience. Not a single old Sparrow had entered the trap. And when I set it for the third time, not one Sparrow went into it—it stood for week after week; the yard was full of Sparrows, but I caught no more. However, I looked forward confidently to the next year—then I thought, young Sparrows will get caught again; and about two dozen would have been enough material for my purpose. But I had reckoned without the intelligence of the Sparrows. When I got out the trap again next year, and had it set, not a Sparrow went into it. But a curious spectacle was observed: apparently several Sparrows had the desire and the intention to go into the trap, and these were obviously the young inexperienced birds which had been hatched since the trap was last set; but others, of course the older birds who had learnt the danger of the wire-basket from the loss of their families, kept them back by constant earnest warnings, for the males, as soon as one of the yellow beaks approached the cage, uttered their warning cry most loudly, the cry which they always make when danger is present, and which consists in a long shrill rattling 'r-r-r-r-r.'"[102] It is well known to poachers that when once a Hare has been netted, there is no chance of its being taken again in like manner. Rather than go through a second time, even though a "lurcher" be but a yard behind, it will either "buck" the gate, or take the fence.[103] Grazing cattle will not touch plants that would be deadly or hurtful to them; but if taken to a distant land, to another continent where unknown herbs grow they are unable to distinguish, they sicken or die of the poison they have eaten.[104]

But perhaps it is only by recognizing the full force of the objections that we can hope to fairly realize the strength of the theory thus called in question. If these mimicking or protective disguises have not been incidental to a phase of evolution, they must have been created as they are, and even the advocates of this view—if any competent are left—would surely not enunciate the idea of a purposeless creation, or the fanciful freaks of a Demiurgos, for such must be the case if no purpose is served by these extraordinary imitations. On the other hand, what can the evolutionist reply when he is confronted with the only other postulate of astonished ignorance expressed in the terms of "a freak of nature"?[105]

The solution of the difficulty may—we repeat—probably be found in ceasing altogether to explain some biological features of the past by causes operating in the present, and perhaps only in the present epoch. In fact, many animals affording undoubted instances of protective resemblance and mimicry now show in the observed dangers of their lives, so little raison d'être for these wonderfully evolved assimilations in colour and structure, that it seems more philosophical to conceive them as survivals of a past when there was a greater danger and a larger need.

(To be continued.)

 

 

BIOLOGICAL SUGGESTIONS.
MIMICRY.

By W.L. Distant.

(Continued from p. 315.)

In all reflections on the wonderful adaptations in nature by which living creatures obtain a protection from their enemies by assimilative colour or structure, we must remember that in the struggle for existence fecundity plays no small part in producing survival. As De Quincey spoke of man in China as being but a weed, so throughout nature we often find excessive reproduction alone preventing extermination, and quite replacing the aid of protective or mimetic disguise in the "survival of the fittest." It is no longer the protection of the few, but the superfluous number of the attacked that militates against annihilation. As Mr. Harting has observed:—"The enormous rate of increase in fish, as compared with the rate of increase in their natural enemies, will always result in there being enough to spare for man and Otter—ay, for Kingfisher and Heron too."[106] Weismann recognizes the same truth in the remark:—"No better arrangement for the maintenance of the species under such circumstances can be imagined than that supplied by diminishing the duration of life, and simultaneously increasing the rapidity of reproduction."[107] Take the Orthoptera as found on the Transvaal veld—where most of these pages were written—which not only during the summer season literally supply the almost sole avian banquet, but are doubtless the prey of other enemies as well; and, although the usual colouration of these insects is more or less approximate to the short grasses among which they live, no apparent protection is afforded thereby, and their great reproductive powers seem their only protection against extinction. The American Lobster is another case in point. Mr. F.H. Herrick, of the United States Fish Commission, who suggests that its habits are the same as that of the European representative, states that out of the 10,000 eggs produced at one time, not more than two arrive at maturity, and that even that estimate is probably too high, as the fisheries are now declining.[108] This diminution may well take place, for, according to Prof. Henry Woodward, of the common species Homarus vulgaris, as many as 25,000 live specimens "are often delivered at Billingsgate in one day. If only as many are eaten in the whole of England as in London, this would be at the rate of 50,000 per day, or 18,250,000 annually.... From Norway as many as 600,000 are received annually."[109] Marine animals commonly produce far more eggs than insects. The dangers of the shallow seas are so great that a small proportion only of the young animals come to maturity. Hence the enormous fertility of common marine animals, except such as are able to nourish or defend their young. Vast numbers of Zoœa are swept into mid-ocean or into tidal rivers, or are devoured. It is only a chance remnant that survives.[110] Prof. Möbius says that out of a million oyster embryos only one individual grows up, a mortality due to untoward currents and surroundings, as well as to hungry mouths.[111] Leuckart calculates that a tapeworm embryo has only about one chance in 83,000,000 of becoming a tapeworm.[112]

The fecundity of fish is shown by the following table of the number of ova in different species, as found by Frank Buckland's observations:—

Name of Fish. Weight of Fish. No. of Eggs.
lb. oz.  
Salmon. (The average num-
ber of eggs in a Salmon is
850 to each pound weight)
12 0 10,000
Trout 1 0 1,008[113]
Carp 14 8 633,350
Perch 3 2 155,620
,, 0 8 20,592[114]

Name of Fish. Weight of Fish. No. of Eggs.
  lb. oz.  
Jack 28 0 292,320
,, 32 0 595,200
,, 4 8 42,840
Roach 0 12 480,480
Conger Eel 28 0 15,191,040
Smelt 0 2 36,652
Lump Fish 2 0 116,640[115]

The Codfish (Gadus morrhua) is a good example of survival through fecundity. In a specimen weighing thirty pounds, with a roe of only four pounds and a quarter, it has been calculated that there were as many as 7,000,000 eggs, and in some cases the number may be 9,000,000.[116] Here, besides other natural enemies, man again is a great destroyer. Describing the Codfishing off the coast of Labrador during the time of his visit (1833), Audubon writes:—"As there may not be less than one hundred schooners or 'pickaxes' in the harbour, three hundred boats resort to the bank each day; and, as each boat may procure two thousand Cods per diem, when Saturday night comes about six hundred thousand fishes have been brought to the harbour."[117] According to Prof. Seeley:—"The banks of Newfoundland and adjacent coasts have been fished since the year 1500. Here one man may take upwards of five hundred fish in a day, and in a year he is reckoned to capture ten thousand, though sometimes fifteen thousand may be caught in a single voyage."[118] As regards the wholesale destruction of the spawn of this fish, a single instance will suffice. In one bird colony alone on the wild coast of Norsk Finmarksen—that of Svaerholt-Klubben—are "millions upon millions" of the small Gull (Rissa tridactyla). The food of these multitudes of birds during the summer months consists for the most part of fish-spawn, more particularly that of the Codfish, which is abundant in these northern waters.[119] The annual take of Herring is prodigious. It has been computed that a million of barrels, representing 800,000,000 fish, are taken in Scotland; the Norwegian Herring fishery is as productive as the Scotch fishery; the English, the Irish, the French, and the Dutch fisheries are also very productive. Estimating the gross produce of these four fisheries at only the same amount as the Scotch fishery, 2,400,000,000 Herring must be annually taken by these four nations—the British, the French, the Dutch, and the Norwegian. Yet the destruction of Herring by man is probably insignificant compared with that wrought by other natural agencies. Mr. James Wilson, in his 'Tour round Scotland and the Isles,' vol. ii. p. 106, says, when describing St. Kilda:—"Let us suppose that there are 200,000 Solan-Geese in the colony of St. Kilda (we believe, from what we saw, the computation moderate), feeding there or thereabouts for seven months in the year. Let us also suppose that each devours (by itself or young) only five Herrings a day—this amounts to one million; seven months (March to September) contain 214 days, by which, if we multiply the above, the product is 214,000,000 of fish for the summer sustenance of a single species near the island of St. Kilda."[120] Cod and Ling, of which three and half millions were taken in Scotland in 1876, feed largely on Herring, six or seven being often found in the stomach of a Cod. These, it is thought, may consume twelve times as many Herring as the four nations together. Gannets, of which 10.000 dwell on Ailsa Craig, must catch more Herring than all the fishermen of Scotland; Whales, Porpoises, Seals, Codfish, Dogfish, predaceous fish of every description, are constantly feeding on them from the moment of their birth. The shoals of Herring in the ocean are always accompanied by flocks of Gulls and other sea-birds, which are continuously preying upon them, and it seems therefore no exaggeration to conclude that man does not destroy one Herring for every fifty destroyed by other enemies. The destructive power of man therefore is insignificant when it is compared with the destructive agencies which nature has created; and nothing that man has done, or is likely to do, has produced, or will probably produce, any appreciable effect on the number of Herring in the open sea.[121] In 1781 the town of Gottenburg alone exported 136,649 barrels, each containing 1200 Herrings, making a total of about 164,000,000; but so rapid was the exhaustion of the fish from this keen pursuit, that in 1799 it was found necessary to prohibit the exportation of them altogether.[122] This is a conclusion somewhat opposed to the opinion of Frank Buckland, as related above; but our aim here is only to show what multifarious dangers the Herring survives.[123]

The Salmon deposits nearly a thousand eggs for every pound of its live weight. But nature is prolific in her waste, and a whole army of her poachers have to be satisfied. "So true is this, that the yearly yield of the largest Salmon-producing river in the kingdom is computed at about the produce of one female fish of from fifteen pounds to twenty pounds in weight."[124] Mr. J.W. Willis Bund, the Chairman of the Severn Fishery Board, estimates that of Salmon eggs only 10 per cent., or 100,000 per million, hatch out. "Nothing Trout like better than Salmon ova; Eels regard it as a delicacy; while Water-hens, Water-Ouzels, Crows, and other birds, as soon as any part of the bed of the stream is either uncovered, or has only a few inches of water in it, go over it again and again, picking out the tit-bits the ova are to them."[125] As to the mortality at the subsequent stages, estimating the number of ova hatched as 1,000,000 out of 10,000,000 in the Severn, it is estimated that between 50 and 75 per cent. of the Alevins pass into the Fry stage, thus bringing the quantity to about 700,000. "In the Fry and Samlet stage the mortality increases to what degree is mere guess, as there is little, if any, evidence; but the mortality must be 50 per cent., so that there would be 350,000 Smolts. Among the Smolts there is also a very high rate of mortality, say, at least 75 per cent., so that the fish that reach the Grilse stage would be something like 40,000 out of 10,000,000 ova, or 4000 per million, about 4 per cent."[126] In Kamschatka the Salmon have probably fewer enemies, as the rivers literally swarm with them; and Guillemard refers to one "little village" where, during the season, "20,000 fish would be no uncommon catch for a single day."[127] The same author describes his impressions when standing on the banks of a little branch of the Avatcha River, not more than eighteen inches deep. "Hundreds were in sight, absolutely touching one another, and, as we crossed the river, our horses nearly stepped upon them. Their back-fins were visible as far as we could see the stream, and aground and gasping in the shallows, and lying dead or dying upon the banks, were hundreds more.... The millions of fish that are caught, and form the food throughout the year of almost every living creature in the country, are, however, as nothing compared with the countless myriads that perish naturally."[128] Krashenniker, writing more than one hundred years ago, says:—"The fish come from the sea in such numbers that they stop the course of the rivers, and cause them to overflow the banks, and when the waters fall there remains a surprising quantity of dead fish upon the shore, which produces an intolerable stink." Guillemard considers that the vast majority—practically all, in fact—ascend the streams to spawn, and, having once done so, die. In the case of some species every fish appears to perish; in others a few get back to the sea.[129] Besides other enemies, when Salmon are abundant and lie close a dreaded disease makes its appearance. This shows as a white fungus about the head and shoulders, and gradually spreads until the fish sickens and dies.[130] The female Sturgeon (Acipenseridæ) deposits enormous numbers of extremely minute eggs, the product of a single individual having been estimated at upwards of three millions during a season. This fecundity is necessary to preserve the species, when, apart from other enemies, we read that upwards of fifteen thousand have been taken by fishermen in a single day at one of the fishing stations on the Russian rivers.[131] Many other instances of great fecundity among fishes might be given, but at least reference may be made to the testimony of Mr. Henry Lee, that a large Octopus produces in one laying, usually extending over three days, a progeny of from 40,000 to 50,000; and the same authority, confirming the observations of Johann Bodasch, found that in the mop-like mass of spawn belonging to a Squid (Loligo vulgaris) there were probably 42,000 perfect young Squids.[132]

Among mammals, the Rat is very prolific. Frank Buckland was told by a trustworthy Westminster ratcatcher that the Rat will breed every seven weeks, and that the female will begin to have young as early as fourteen weeks old.[133] The same author, referring to a little book on the Rat written by a Mr. Shaw, "of ratcatching notoriety," states that "his little dog Tiny, under six pounds weight, has destroyed two thousand five hundred and twenty-five Rats, which, had they been permitted to live, would, at the end of three years, have produced one thousand six hundred and thirty-three millions, one hundred and ninety thousand, two hundred living Rats."[134] "Every wild Rabbit who lives to old age has probably been concerned during its life as one of two partners in the production of not less than three hundred young Rabbits." Yet in England no perceptible increase is visible, and we must conclude "that out of three hundred Rabbits born, only two survive to middle age, on the average; the rest being either killed and eaten by carnivorous animals, or (more rarely) dying through inability, for some reason or another, to obtain food."[135] The Hamster (Cricetus frumentarius) possesses marvellous powers of reproduction, and frequently appears in countless swarms. They have a host of enemies, and Buzzards, Owls, Ravens, and other predaceous birds thin their ranks by hundreds; while among four-footed foes, Polecats and Stoats follow the track of the advancing legions, and kill them where and when they can. The Polecat and Stoat are, moreover, able to follow the Hamster into the recesses of their burrows, where they probably destroy them by hundreds.[136]

Innumerable illustrations might be chosen from the life-histories of insects. Prof. Miall observes:—"Winter, of course, brings many hardships upon aquatic insects, as the great reduction in their number proves. The enormous number of eggs laid by so many of them is doubtless connected with the heavy risks to which they are exposed during half the year."[137] Of one of the May-flies (Polymitarcys virgo) Réaumur states:—"The short life of the winged female compels her to deposit her 700 or 800 eggs at once, without much discrimination of likely and unlikely places." Of the Pine Sawfly (Lophyrus pini), whose larvae are frequently found in such numbers in pine-woods, it has been said:—"When young, and also just before turning into pupæ, the grubs are very susceptible to sudden cold or heavy rain, which kill off thousands. In addition to these destructive agencies, nearly forty different kinds of parasites infest the grubs, while mice devour numbers of the pupæ."[138] Among the Threadworms (Nemathelminthes) parasitic Nematodes produce enormous numbers of eggs. Van Beneden states that 60,000,000 have been computed in a single Nematode, and this multiplication of ova is absolutely necessary, for the chance of the embryo reaching the right host, in which alone it can develop, is always a small one.[139]

This excessive fecundity in some animal life finds its parallel in plants. Thus it has been computed that a plant of Sisymbrium sophia yields 730,000, one of Nicotiana tabacum 360,000, one of Erigeron canadense 120,000, and one of Capsella bursa-pastoris 64,000 seeds yearly.[140] Probably in this case, and in a state of nature, a great check to increase is to be found in the difficulty the seeds experience in finding a proper soil in which to germinate, as well as in other sources of destruction.

The advantages of, or the part played by fecundity in the preservation of many species is evidently of the most complete and far-reaching character. This seems particularly and more frequently the case with fishes,[141] the reasons for which are not difficult to comprehend. It has been urged that the pale colour of the under side of fishes makes it more difficult for enemies to detect them from beneath; but this is probably a truism without denoting any evolved protection, and may be due to other causes. The survival is probably owing to fecundity alone, which prevents extermination from the many foes and adverse conditions which environ their lives. One may stand before the tank in a large aquarium, and be impressed with the assimilative colouration of the upper sides of flat-fishes to the sandy or pebbly bottom on which they rest, but still no difficulty is experienced in distinguishing the living creatures; and if this be so, and with our untrained perceptions, how much stronger must be the detective powers of those natural enemies whose prey is their necessity! The 130,000 eggs said to be carried by a Sole of one pound weight is probably the factor which prevents annihilation, and not a moderate disguise which, without deceiving ourselves, is still less likely to mislead enemies whose lives depend on its destruction. Nature is here quite "careless of the single life," but, by fecundity, "so careful of the type." In our oceans and rivers the course of evolution has decided that the most prolific shall survive, and this is probably with fish the great factor of protection. Here individuality is lost, and Providence is with the big battalions. If there is truth in this view, it should be emphasized by the fact that animals of great fecundity, as a rule, possess little protective disguise in colouration or markings, and this, in a great measure, appears to be the case, despite the somewhat contrary evidence which tends to be deducible from the colours of many flat-fishes. Even in this case we must remember that other senses besides those of sight may be used to discover a semi-concealed prey. The extreme hardihood of certain animals after injury is also an agency in "survival." Prof. Mcintosh relates that "a full-grown female Picked-Dogfish was captured in the stake-nets for Salmon some years ago with its stomach distended with food. In dissecting the apparently dead animal in the laboratory the heart pulsated actively, though it and the pericardium were covered with old and recent lymph, caused by the irritation of a large Cod-hook, the point of which projected into the pericardium, and against which the heart seemed to impinge during contraction. An Eel will live for a year or two with a hook projecting through the gut into the abdomen, and the glutinous Hag (Myxine) is also hardy under similar circumstances."[142] In so often seeking for the explanation of animal survival by mimetic or assimilative disguises, we are probably endeavouring to open too many locks with one key.


Colour alone may prove a false analogy to protection. Mr. Beddard has well observed:—"The bluish and white colour of many Gulls is generally allowed to be of protective value; in any case, they are not unlike their usual surroundings. For three years several of the common species of Gulls have a brownish speckled plumage, which is totally unlike that of the old bird; if one colour is advantageous, the other must be the reverse; and three years is either a considerable period, or not long enough."[143] Another illustration is from a writer who, recording his views as to protective resemblances in South America, describes the wellknown butterfly, Ageronia feronica, which rests with its wings expanded horizontally. When seen on the "grey lichens or bark of the tree-trunk," it is "then so like in colour and markings to the surface on which it rests that it is practically invisible at the distance of even a few yards."[144] This observer, however, at the same time refers to the statement of Bigg Wither, that this very insect is called the Whip-butterfly, owing to the sharp whip-cracking sound made by its wings when battling with its fellows in the air, and that this sound makes it the easy prey of a forest-bird, locally known as the "Suruqua," who thus detects and secures it. Here the apparent protection, by "protective resemblance," is invalidated by a peculiar and unusual sound-producing quality, which is as equally dangerous as its colour is reported protective. A similar remark may be made as to the musical Cicadidæ. How often have the usual green and brown colours of these insects been adduced as an example of protective resemblance, and not without reason if we regard only the difficulty of distinguishing them on the branches or leaves on which they rest. But when we desire to capture them, their shrill noise proclaims their retreat, and their assimilative colouration avails them little. This has frequently been the experience of the writer when in South Africa.[145] Mr. Burr writes:—"I have often stalked down our large Locusta viridissima, L., and have usually found it on a bed of nettles or thistles, in the middle of a corn-field, or in stubble, invariably much farther away than I at first expected. The sound appears to come from almost beneath one's feet, but, on walking straight towards it, seems to recede into the distance, until it suddenly strikes the ear, very harshly and shrilly at close quarters. As soon as the would-be capturer approaches the sound ceases, and the insect remains invisible. The assimilation of the green colour of the insect and the green surroundings, which it always chooses as a band-stand, is so close, that it is almost impossible to detect the creature until it recommences to chirp, when the rapid movement of the elytra betrays its whereabouts."[146] Frank Buckland wrote similarly of the Green Tree-Frogs of Germany:—"I have frequently heard one singing in a small bush, and, though I have searched carefully, have not been able to find him; the only way is to remain quite quiet till he again begins his song."[147]

The aquatic larvae known as the Small "Bloodworm" (Tubifex rivulorum) is another instance of an animal whose colouration is a lure to its destruction, and whose fecundity can alone enable it to survive. The angler knows how readily a dish of Gudgeon can be procured with this bait; whilst other well-known ground fishes, such as the Loach (Cobitis barbatula), and the Miller's-thumb (Cottus gobio) also greedily attack it. These small worms live in great numbers in the mud at the bottom of streams, and, as Mr. Beddard has observed, as "the head-end is fixed in the mud, while the tail waves about freely in the water, these worms form exceedingly conspicuous red patches, which must attract ground-feeding fish."[148]

It is often urged that few observers have seen butterflies attacked by birds, and that therefore their protective and warning colours are little needed against these as foes. Similar remarks have been made with reference to other animals. Thus Mr. Andrew Lang writes:—"On the Dee, Salmon sometimes rise to March Browns, and take the artificial March Brown tied rather large on these occasions. I have never seen a Salmon take a natural fly, any more than I have seen a phantasm of the dead"; yet he adds he "can believe on good evidence that Salmon do take natural flies."[149] Undoubted trustworthy accounts do exist also as to avian attacks on Lepidoptera, and the writer has witnessed not a few, though the occurrence is somewhat uncommon. Eimer once came across a large concourse of white and blue butterflies on a high plateau of the Swabian Alp: "On my approach a number of birds (Stonechats) flew from the spot, and when I came up I found a number of maimed butterflies lying fluttering on the ground; pieces had been bitten from the wings of most of them—indeed the wings were often torn to pieces before the birds succeeded in getting the bodies of the butterflies, although these were sitting quietly on the ground."[150] Mr. Riley Fortune states that he has often seen Starlings chasing butterflies.[151] The Stonechat greedily devours butterflies, as I have seen in the aviaries of Dr. Butler. Zehntner on different occasions found seven Painted Lady butterflies in the mouths of Alpine Swifts (Cypselus melba), as recorded in the 'Catalogue des Oiseaux de la Suisse.'[152] Such an observation did not miss the lynx eyes of Jefferies: "I once saw a Flycatcher rush after a buff-coloured moth, which fluttered aimlessly out of a shady recess; he snapped it, held it a second or two while hovering in the air, and then let it go. Instantly a Swallow swooped down, caught the moth, and bore it thirty or forty feet high, then dropped it, when, as the moth came slowly down, another Swallow seized it and carried it some yards and then left hold, and the poor creature after all went free. I have seen other instances of Swallows catching good-sized moths to let them go again."[153] These moths were probably inedible species, and were thus protected, at least at this stage of their existence. Mr. Furneaux, referring to the common and well-known white butterflies of the British Pieridæ, observes: "It is remarkable that we are so plagued with 'whites' seeing that they have so many enemies. Many of the insect-feeding birds commit fearful havoc among their larvae, and often chase the perfect insect on the wing."[154] Another writer states: "At no stage in their lives are lepidopterous insects free from the attacks of enemies. In the egg state they fall a prey to beetles and small birds, and as larvæ they are extremely liable to receive a deadly thrust with the ovipositor (or sting) of an ichneumon.... The enemies of the imago, whether butterflies or moths, are numerous. Birds, Bats, dragonflies, &c, pursue and harass them whenever they happen to meet with them."[155] Fungi are also parasitic on butterflies.[156] But the discrepancy in experience as found among field naturalists on these points tends to prove how partial or moderate must be the danger in the present day, and how considerably more intense it must have been in some former time to have prompted the evolution of the wonderfully simulating guises, which we can only conceive as evolved for protective purposes.

A repetition of observations will frequently qualify the premises on which many conclusions are based. Many recorded facts are of course utterly erroneous. Thus in 1666 Schefferus records in the 'Philosophical Transactions' that Swallows sink into lakes in autumn, and hibernate in a manner precisely similar to Frogs. In 1741 Fermier-Général Witkowski made legal testimony to the effect that two Swallows had been taken from a pond at Didlacken in his presence in a torpid state; that they eventually regained animation, and after fluttering about, died some three hours after their capture. In 1748 the great Swedish chemist Wallerius wrote that he had on several occasions seen Swallows clustering on a reed until they all disappeared beneath the surface.[157] Thus a traveller in a tropical forest might from paucity of observation form a wrong impression as to the relation of the liane and the stem or tree to which it is attached. He would frequently find "the hard basal parts of a liane stem twisted and coiled apparently around nothing. This is due to the fact that the original support had been killed, and then, slowly rotting into dust, has been denuded away by the wind and rain." Our traveller might then record the murderous action of lianes as of a somewhat universal character. But further observations would show the action quite reversed. As Kerner describes the process: "If the erect young stem is stronger and more vigorous than the twiner which encircles it, which has been used as a prop, it does not allow itself to be strangled; the twiner is destroyed when they both increase in thickness. The coils of the climber are gradually stretched tighter and tighter, and many are the contrivances which exist for preventing the tension from immediately acting injuriously on the movement of the sap in the interior of the twining liane stem. As this thickening continues, the pull on the coils becomes so great that the death of the liane results."[158] Similarly an explanation may be long deferred till one branch of science is sufficiently advanced to illuminate another. Discoveries in botany and entomology have often reacted on, and supplemented each other. Prof. Drummond has quoted an instance which will serve our purpose here:—"More than two thousand years ago Herodotus observed a remarkable custom in Egypt. At a certain season of the year the Egyptians went into the desert, cut off branches from the wild palms, and, bringing them back to their gardens, waved them over the flowers of the date palm. Why they performed this ceremony they did not know; but they knew that if they neglected it the date crop would be poor or wholly lost. Herodotus offers the quaint explanation that along with these branches came certain flies possessed of a 'vivific virtue,' which somehow lent an exuberant fertility to the dates. But the true rationale of the incantation is now explained. Palm trees, like human beings, are male and female. The garden plants, the date bearers, were females; the desert plants were males; and the waving of the branches over the females meant the transference of the fertilizing pollen dust from the one to the other."[159]

 

The time has arrived when the whole theory of "protective resemblance" and (or) "mimicry"[160] requires to be expressed and understood in two senses, viz. Demonstrated, and Suggested or Probable. I propose also to give instances of what may be considered as Disputed or Mistaken Mimicry, and likewise Purposeless Mimicry. In considering these questions one is reminded of the three kinds of Phantasms as understood by the Stoics. Those that were probable, those that were improbable, and those that were neither one nor the other. Or perhaps still better, the three categories of Renan. "The first, which is unfortunately very limited, is the category of certainties; the second, that of probabilities; and the third, that of dreams,"[161] By the term "Demonstrable" is implied all those instances where protection, absolute or partial, has been or can be demonstrated by experiment or actual observation. "Suggested or Probable" should, however, be applied to those examples where, because we see similarity of structure, markings, or colour, we assume—and probably often correctly—that protection is involved, though no direct knowledge of the same is obtainable. As an illustration, we know that certain Diptera, Eristalis spp., resemble Bees, and we conclude that this simulation has arisen by evolutionary means for protective purposes. It must nevertheless be remembered that the Bee itself is not absolutely protected by its sting, and does not possess a corresponding immunity from the attacks of all its enemies. Mr. Woodford, on Peel Island, Moreton Bay, observed Bees of the genus Bombus caught and devoured by Spiders.[162] Prof. Lloyd Morgan's experiments, however, demonstrate protection at least from birds:—"To another group of chicks I just gave Hive Bees, which were seized, but soon let alone, and then the Droneflies (Eristalis), which so closely mimic the Hive Bee. They were left untouched. Their resemblance to the Bees was protective."[163] Frank Buckland relates:—"A gentleman in Oxfordshire had a hive of Bees in the cavity of a wall. A common Toad which had taken up its residence in a hole close by was observed to walk forth and place himself at the mouth of the hive, and so catch the Bees in their coming from and returning to the hive with much dexterity and activity. After witnessing the Toad at work for some time, and feeling convinced that, if his depredations were suffered, he would eventually destroy the whole hive, the owner of the Bees killed the robber, and on inspecting his stomach it was found full to repletion of dead Bees."[164]

No specialist who works long at any large group of animal forms, especially at insects, can escape meeting with these problems. This is particularly discovered when, in monographing a family, species are found resembling insects belonging to another order. Thus, in recently working out some Hemiptera for the 'Biologia Centrali-Americana,' I found in the family Lygæidæ a species with all the superficial form and colour of an Earwig (Forficula) belonging to the order Orthoptera; while among the Lygæidæ and Capsidæ were many species which mimicked Ants (Hymenoptera). To add to the problem, Lygæidæ and Capsidæ were found mimicking one another. Dr. Thorell made a similar observation in monographing Burmese Spiders. Ligdus chelifer "is a small flat Spider belonging to the family Salticoidæ, and resembles very much a Cheloneth (Pseudoscorpion); Prolochus longiceps has some resemblance to an Orbitelarian Spider of the genus Meta (M. segmentata, f. inst.)."[165] Now, in the first case, and, alluding to the writer's own experience, it appears we have "Suggested or Probable Mimicry," because we possess no knowledge whether these Hemiptera are found with the Earwigs and Ants they mimic, nor whether they are avoided or neglected by enemies because of this mimicry. We can only report that these insects are mimics one of another as seen in our cabinets, and that as nothing is, or can be, predicated as purposeless in nature, neither can these assimilative forms be meaningless; and, further, arguing from demonstrated knowledge in other cases of mimicry being protective, the presumptive evidence is that the theory of protection affords the clue to the origin of the mimetic guise of these insects. But this is only circumstantial evidence of the weakest description, and, though we may believe as a matter of biological faith, based on analogous cases in nature, that this is the explanation, it is probable, or more than probable, that the progress of science is retarded by confounding scientific suggestion with scientific demonstration.[166] It is simply teleology come back to the house newly swept and garnished. To the teleologist everything in nature proclaimed design, and a precisely similar view—only differing in terminology—is held by an extreme wing of our own Darwinian army; the only distinction is, that the design in one case was attributed to a supernatural providence, in the other, to an all-sufficing power represented by the term Natural Selection. That the teleologist was in no way inferior, but in many instances—so far as power of observation was concerned—surpassed the knowledge of many of our contemporary entomological evolutionists, is a fact that can be easily realized by perusing the exhaustive Letter XXI. in Kirby and Spence's 'Introduction to Entomology,' on "The means by which insects defend themselves." In this letter may be found a wealth of illustration on what we understand as "protective resemblance," &c, not available in any special work written on that theory. How near to modern thought the writer of that letter was, is proved by its last paragraph:—"Another idea that upon this occasion must force itself into our mind is, that nothing is made in vain. When we find that so many seemingly trivial variations in the colour, clothing, form, structure, motions, habits, and economy of insects are of very great importance to them, we may safely conclude that the peculiarities in all these respects, of which we do not yet know the use, are equally necessary; and we may almost say, reversing the words of our Saviour, that not a hair is given to them without our Heavenly Father." Even when teleological views and the conception of a special creation dominated the minds of naturalists, the knowledge of the existence of intermediate forms—a postulate of modern evolution—was more or less enunciated. Thus, in the first part of the 'Zoological Transactions,' Mr. Ogilby, in describing the Cynictis Steedmanii, a mammal just then discovered in South Africa, remarks: "That the work of creation was originally complete and perfect in all its parts; that no hiatus existed among natural bodies, or, in other words, that no individual stood completely apart from surrounding groups, but that all were connected by a uniform gradation of intermediate forms and characters, is a law of natural history which every day's experience tends more strongly to confirm."[167] We sometimes find teleological views in what are presumably put forward as evolutionary suggestions. Thus Mr. Harting, in discussing the migrations of Ceylonese butterflies, is inclined to concur with Col. Swinhoe, in considering the explanation "as a sudden exodus from the birthplace, leading to a compensating reduction of the species, after a season exceptionally favourable to its increase."[168] This "compensating reduction," or rather the method of the same, as thus expressed, seems more logically to denote design or chance, neither of which will explain the phenomena, but may reasonably be adduced to account for the theory. Perhaps one of the most orthodox and thoroughgoing teleologists was the late Frank Buckland, to whom the poisonous fangs of deadly Snakes were "the apparatus which the omniscient Creator has given to the class of Snakes to enable them to procure their food"; though, he might have added, these divinely-constructed creatures are on that very account gladly destroyed by the orthodox and heretical alike. The real difference between the teleologist and the evolutionist appears to be this. Both search for the phenomenal facts in animal life, but, when found, the teleologist goes no further than enunciating the magical word "Design." The evolutionist, on the contrary, seeks to find how the structure or property has been, and from whence, derived. With the first it is "Fall down and worship"; with the second, "Prove all things." Agassiz considered that the only classification of the animal kingdom was to be found in the plan of creation; "the free conception of the Almighty Intellect matured in His thought before it was manifested in tangible external forms."[169] And again: "I would as soon cease to believe in the existence of one God because men worship Him in so many different ways, or because they even worship gods of their own making, as to distrust the evidence of my own senses respecting the existence of a pre-established and duly-considered system in nature, the arrangement of which preceded the creation of all things that exist."[170]

What we seem to require is a healthy Agnosticism in theoretical science; neither affirmation nor negation, per se, but proof. Thus, grant to all a free use of the imagination in scientific theory, but in no case allow it to be confounded with fact, or crystallized into dogma. "What is called 'mimicry' is apparently, in many cases, nothing more than the influence of similar surroundings, acting in a similar manner upon different insects inhabiting the same district."[171] Or, as Mr. F.T. Mott most enigmatically puts the objection, "The very curious appearances of mimicry, which are often supposed to be protective, but of which a large proportion seem to have no such function, may probably be attributed to sympathetic communication of the vibratory motions which must be passing through the ether in all directions in the neighbourhood of organic life."[172] Animal depredators may, however, be not altogether defeated by "mimicry," which of course predicates the sense of sight only. As Mr. Cornish has well observed, predaceous animals watch for movement to guide them to their prey. "Most of the larger birds, notably Wood Pigeons, remain perfectly motionless for many seconds after alighting in a new place, in order to identify any moving object. On the other hand, the power of scent is a great corrective to animal misconceptions about objects."[173] How little is the cause of Darwinism advanced by many exhibitions made at scientific societies! The advocate exhibits—say, insects—which, belonging to different orders, closely resemble each other in colour, markings, or structure, and which he reasonably adduces as an example of "mimicry," but misuses a suggestion as a demonstration. The Darwinian sceptic at once denies the strength of the whole argument, because it cannot be demonstrated as a fact, and has not been put forward as a suggestion only. It is quite possible that truth may exist between the two antagonists, for it seems certain we have not yet all the explanations of these mimetic disguises, and discussion may well precede a universal dogma of its causation. Because a phenomenon is frequent in nature, it is not necessarily universal. For instance, the metamorphosis in the early lives of Frogs is an observation of so general a nature as to indicate a constant law; but a land Frog in the Solomon Islands (Rana opisthodon) lays very large eggs in the crevices of rocks, and from these emerge fully-developed Frogs.[174] We join issue with Prof. Tyler when he states, "Natural science does not deal in demonstrations, it rests upon the doctrine of probabilities; just as we have to order our whole lives according to this doctrine."[175] This is a cardinal doctrine in natural and apologetic theology, but is the very antithesis of science, natural or otherwise. The man who orders his whole life on probabilities will probably arrive at the conclusion that hope is a very good breakfast, but a most indifferent dinner. A "science" based on probabilities may turn out to be a new system founded on contradictions.

Prof. Herdman, in speaking of the colours of Nudibranchs and their probably protective character, forcibly observes that we cannot gauge the problem by observing the animals in a museum-jar, or as illustrated in a book, or on the wall. "In order to interpret correctly the effect of their form and colours, we must see them alive and at home, and we must experiment upon their edibility or otherwise in the tanks of our biological stations."[176] Such a course would doubtless give many positive and many negative results, confirming in many cases the theory—if it is still to called but a theory—of mimicry, and preventing many hasty and erroneous conclusions in other cases, where mimicry is only a suggestion, and much discredit is brought to the argument. The "law of evidence" might with advantage be studied by many enthusiastic students in bionomics. Solitary instances, or that of a single species without reference to its congeneric allies, afford but a doubtful testimony to mimetic resemblances. This was clearly seen and enunciated by Darwin himself:—"If Green Woodpeckers alone had existed, and we did not know that there were many black and pied kinds, I dare say that we should have thought that the green colour was a beautiful adaptation to conceal this tree-frequenting bird from its enemies; and consequently that it was a character of importance, and had been acquired through natural selection; as it is, the colour is probably in chief part due to sexual selection."[177] In fact, much evolutionary controversy is simply intellectual fencing, and what Schopenhauer has defined as "controversial Dialectic, Dialectica eristica." Mimicry, again, is often much obscured by plates in illustrated books which are intended to support the theory. As an example, in the excellent 'Royal Natural History'[178] appears a coloured plate, entitled "Mimicry in Insects." Here a number of various insects of different orders and diverse habits are brought together in the midst of inappropriate—or inartistic—foliage, with the result that there is no apparent or sufficient mimicry to deceive the most careless enemy, or the most inexperienced entomologist. In fact, as a support to the theory, one can only conclude that either nature, or the artist, is at fault. Again, a comparative immunity from attack is often ultimately proved to be alone the case. A recent writer has observed:—"It is well known, and I have myself observed, that all our 'Cabbage' Butterflies are immune from attacks of birds,[179] presumably because of some unpleasant taste or smell. Wasps, however, have twice been observed by me in the act of devouring these butterflies. Earwigs, too, which undoubtedly possess an unpleasant smell when irritated, fall victims to Wasps, in spite of their malodorous attributes."[180]

To conclude a discursus, which in itself appears somewhat controversial, it may be better to give some instances of what are considered as "demonstrated,"[181] and others classed as "suggested or probable," illustrations of the theory of mimicry; and it will be noticed that those in the second category are much more numerous than those included in the first; inference necessarily having so often to be relied upon in the absence of observed facts.

 

(To be continued.)

 

 

BIOLOGICAL SUGGESTIONS.
MIMICRY.

By W. L. Distant.

(Continued from p. 363.)

In the following discussion on "Demonstrated," "Suggested or Probable," and other categories of views and suggestions relating to this more than interesting question, recourse has been somewhat plentifully made to original quotations, giving full references to the authors and publication of the same. This course may be probably commended for several reasons. In the present day much biology is written on the historical method,[182] in which conclusions and facts are worked together in one harmonious whole, and treated as canonical information, to which reference to the original sources of information is unnecessary. But in Biology, surely we should bear in mind—(1) Justice to the original author—A. Reference to the work in which the quotation appears, and which may be unknown or neglected by the reader, who may thus—(a) find other facts besides those quoted; (b) find that such quotations should be qualified by other information in the same work; (c) be led to consult the same authorities with reference to other investigations he may have in hand. Besides which, the evidence for or against this theory must be cumulative, and we must not be misled by successful advocacy either one way or the other.

 

Illustrations of Demonstrated Mimicry.

Butterflies of other families are found as mimics of the Danaidæ and Heliconiidæ, which have been shown to be generally uneatable, and avoided by Birds, Dragonflies, Lizards, and other enemies. The fact that the writer found a Danais chrysippus being devoured by an orthopterous insect (Hemisaga prædatoria)[183] is only another illustration of the much used motto—the exception proves the rule. The glands near the anus of some Heliconiidæ have also been proved to emit a pungent odour. These facts have been recorded by Bates, Belt, Trimen, Wallace, and others. But Mr. Frank Finn, who has made some careful experiments to test the "Theory of Warning Colours and Mimicry," certainly found that his birds in captivity not only ate, but sometimes seemed to prefer, specimens of Danais and Euplœa. Nevertheless, when he experimented with birds at liberty, he had not the slightest doubt "as to the unpalatability of Danais, and the other 'warningly-coloured' forms. Birds would often look at them, and soon left them when picked up." But when he further experimented with the common garden Lizard of India (Calotes versicolor), he came to the conclusion that "the behaviour of these reptiles certainly does not appear to afford support to the belief that the butterflies at any rate, usually considered nauseous, are distasteful to them."[184]

Miss Newbigin is also a sceptic on this point, based on her physiological study of animal colouration. She remarks:—"Instead therefore of supposing that the Heliconiidæ have, in Mr. Wallace's words, 'acquired lazy habits' and a slow flight because they are uneatable, and the Pieridæ because they resemble the Heliconiidæ, may we not rather suppose that the slow flight and 'warning' colours in both cases are due to the same cause, the relatively low organisation which renders pigmentation by waste products possible, which makes brilliant optical colours impossible?"[185] As appertaining to this subject, Mr. Hopkins has demonstrated the presence of uric acid in the wing-pigments of the Pieridæ, and observes:—"The described uric acid derivatives, though universal in the Pieridæ, are apparently confined to this group among the Rhopalocera. This fact enables the interesting observation to be made, that where a Pierid mimics an insect belonging to another family, the pigments in the two cases are chemically quite distinct. This is well seen in the genera Leptalis and Mechanitis respectively."[186] The experiments and conclusions of Dr. McNunn and Miss Newbigin in relation to the green pigments in Invertebrates have already been referred to in these pages (ante, p. 430).

The leaf-like Phasmid (cf. ante, p. 303) observed by Mr Belt standing immovable among a host of foraging ants, many of which ran over its legs without discovery that food was within their reach.[187] (This may also be taken as an illustration of "Active Mimicry," referred to subsequently.)

The larvæ of Geometrid Moths, which so resemble the twigs on which they rest as to deceive their enemies. Rösel's gardener, mistaking one of these caterpillars for a dead twig, started back in great alarm when, upon attempting to break it off, he found it was a living animal.[188] Burmeister was similarly deceived by the larva of Ph. quercinaria, Borkh. (Eunomus erosaria, Tr.), "mistaking it for a small dry twig upon wishing to break off a small twig of oak."[189] Mr. Jenner Weir writes:—"After being thirty years an entomologist, I was deceived myself, and took out my pruning-scissors to cut from a plum-tree a spur which I thought I had overlooked. This turned out to be the larva of a Geometer two inches long. I showed it to several members of my family, and defined a space of four inches in which it was to be seen, but none of them could perceive that it was a caterpillar."[190]

In plants, Matricaria chamomilla is considered a mimic of the true Chamomile, which from its bitterness is not eaten by quadrupeds. Ajuga chamæpitys is a mimic of Euphorbia cyparissias, with which it often grows, and which is protected by its acrid juice. The most familiar case, however, is that of the Stinging and the Dead Nettles. They very generally grow together, and, though belonging to quite different families, are so similar that they are constantly mistaken for one another.[191] But even here caution is necessary in many cases before giving a verdict for mimicry as generally understood. Zopf (1892), in studying the colouring-matter of the fungus Pilobolus, found that a parasite growing on the fungus took up not only the drops of oil, but also the pigment associated with the oil, the result being that parasite and host were similarly coloured.[192] Poulton has also shown that the green pigment of some caterpillars is derived from the green leaves upon which they live.

It is to be remembered, however, as Mr. Ridley has remarked, that it is not essential that fruits should be flavoured to our taste in order to induce birds or animals to swallow them. In the Malay Peninsula "the Macaranga capsules, covered with a viscid gum most unpleasant to the mouth, the hot Capsicums, the drupes of the palms (Kentia macarthuri), the berries of the wild grapes (Cissus spp.), which have a most irritating effect on the mouth, and the poisonous fruits of Sapium, are all highly popular with birds, and even the fruit of Strychnos tieute, Bl., with its intensely bitter pulp, is eaten by Civet Cats. A large number of the wild fruits, too, though very astringent, are sometimes eaten by birds or animals."[193] In the North-West Provinces of India, Mr. Silberrard has known Goats to "frequently eat, without any ill-effect, the leaves and green stems of the 'Akaúa' or 'Madar' (Asclepias or Calotropis gigantea), the milky juice of which is an acrid poison for human beings, and is frequently used as such in infanticide cases."[194]

 

Illustrations of Suggested or Probable Mimicry.

We do not suggest, or in any sense imply, that the few and scanty instances we have given of "Demonstrated Mimicry" are at all commensurate with the much larger number that could be adduced. But an illustration was alone intended. In the present category the records are, however, much more numerous, and considerably more familiar, to all who take an interest in the subject. We are now in the realm of suggestion, and among naturalists who incline to theory there is often much faith. As Lecky has observed, referring to another subject, "Their measure of probability ultimately determines the details of their creed."[195]

Recently a new suggestion has been made as to "Nocturnal Protective Colouration in Mammalia, Birds, Fishes, Insects, &c, as developed by Natural Selection." The author, Mr. A.E. Verrill, truly remarks that much has been written in respect to the imitative and protective colours of these groups, as seen by daylight, and the bearing of these facts on natural selection is well known. Very little attention has been paid to their colours, as seen by twilight, moonlight, and starlight. Yet it is evident that protection is more needed during the night than in the daytime by a very large number of species. This is the case with those that move about in search of their food at night, as is the habit of numerous forms of small mammals, such as rodents (Rats, Mice, Arvicolæ, &c), insectivores (Moles, Shrews, &c), many herbivores, various marsupials, and members of other orders. Many carnivorous species, which seek their prey at night, will also find advantages in such protective colours, for thus they will more easily escape the notice of their prey. Hence many nocturnal carnivores are black or nearly so, as the Mink, Fishes, some Bears, &c. The same principles will apply to birds, reptiles, fishes, and to insects, both in their larval and adult states, for many members of all these groups are very active at night, and hide away in holes or beneath dense herbage by day.... Many nocturnal insects that live on the ground are black or dark brown, which are colours that are protective only at night. This is true of most ground-beetles, many Crickets, Cockroaches, Ants, &c. Many of these insects hide away in the daytime, so that no protective colours are then needed. But many insects that are exposed both during the day and at night have acquired green or yellowish colours that are protective at all times, when living among foliage. Green-grasshoppers, Katydids, &c, are examples."[196]

Sometimes we find varied or almost contradictory suggestions, as has been applied to the resemblance of Tree-Shrews to Squirrels. Lydekker considers this may have been originally due to the extreme agility of the latter animals insuring them from pursuit by other creatures, as being a useless task. Hence it would clearly be an advantage for a slower animal to be mistaken for a Squirrel.[197] Wallace suggests that the resemblance is probably due to the Squirrels being harmless creatures which cannot alarm the insects around them by their movements, so that the Insectivora which resemble them easily capture their food.[198] Another protective quality possessed by Squirrels has been conjectured by Poulton as existing in its large bushy tail: "An enemy in pursuit would be liable to get only a mouthful of fur."[199] Ridley, in commenting on this proposed mimicry, is much more cautious: "If this resemblance is to be reckoned an example of mimicry, it is not easy to decide whether it is the Tupaia which mimics the Squirrel, or the Squirrel the Tupaia. Possibly the resemblance is accidental, both animals having taken on the most inconspicuous colouring, and the most suitable form for their environment."[200] Mr. Oldfield Thomas considers that the resemblance between the Bassaricyon, a Raccoon-like type of animal (known at present only by a single skull from Costa Rica and a skin from Ecuador)[201] to the Kinkajou (Cercoleptes caudivolvulus), a well-known Raccoon inhabiting Central America and Northern Brazil, is a case of true mimicry, although he is unable to imagine of what advantage it can be for the Bassaricyon to be mistaken for a Kinkajou.[202] The Cape Hunting-Dog (Lycaon pictus) has a superficial resemblance to the Spotted Hyæna of the same country, which has been suggested as a case of mimicry. As Mr. Lydekker has observed:—"It is, however, very difficult to see what advantage a strong animal hunting in packs, like the present species, can gain in being mistaken for a Hysena, as it is in every respect fully qualified to take care of itself. If, however, we could suppose that the Hunting-Dog was originally a solitary animal, which had subsequently become gregarious, then perhaps the resemblance to the Hyæna might have been an advantage to it."[203] The same authority believes that in the resemblance of the South African Weasel (Pœcilogale albinucha) to the Cape Polecat (Ictonyx zorilla) we may have "another instance of true mimicry among mammals."[204] The African Monkey (Colobus occidentalis) is covered with a long silky fur arranged in alternate stripes of black and white, so handsome that the skin is much prized by the Masai for making head ornaments. The contrast of black and white is so marked that at first sight, as Dr. Gregory remarks, "it would seem to preclude concealment, but its value is at once evident when the animal is seen at home. This Monkey lives in the high forests of Abyssinia, Kenya, Kilima Njaro, and Settima, where the trees have black trunks and branches, draped with long grey masses of beard-moss or lichen. As the Monkeys hang from the branches they so closely resemble the lichen that I found it impossible to recognize them when but a short distance away."[205]

The tabby Cat, the original progenitor of which may have been "a distinct natural variety which no longer exists as a wild animal," has been thus described:—When "curled up asleep, the dark bands arranged themselves in concentric circles, or rather in a closely set spiral, strongly suggesting the appearance of a coiled serpent."This is considered as a probable remarkable instance of "protective mimicry."[206]

Mr. S.E. Peal, writing from Assam, has launched the following suggestion: Certain tan-spots occur over the eyes of semi-domesticated Dogs. They do not exist in wild animals allied to the Dog, or in the modern breeds of fully-domesticated Dogs. The spots are most conspicuous when the eyes are closed, appearing then like opened eyes. They "may have been protective to the animals during sleep, causing them to look as if wide awake." This speculation has been supported by no less an authority than Mr. A.R. Wallace.[207] Waterton, in describing the South American Sloth, writes: "His fur has so much the hue of the moss which grows on the branches of the trees that it is very difficult to make him out when he is at rest."[208] The Philippine Koel, or Phow (Eudynamis mindanensis), one of the Cuckoos, is an example of a bird in which the young does not follow the general rule of having the plumage of the female, or one distinct from that of both parents. Mr. Whitehead accounts for this by the fact of the Phow laying its eggs in the nest of the Yellow-wattled Myna. "The young Cuckoo, being black, does not differ from the young Myna, and so the deception is carried on until the young bird can take care of itself. If the young followed the general rule, and resembled their mother in being of a brown colour, the Mynas might not feed them."[209] Of the Matamata Tortoise (Chelys fimbriata), a South American species, it has been observed:—"When in its native element the warty appendages on the neck float in the water like some vegetable growth, while the rugged and bossed shell strongly resembles a stone; it is thus probable that the whole appearance of the creature is advantageous either in deluding its enemies or in attracting to it the animals on which it feeds, the latter being the most likely hypothesis. Although it appears that the Matamata will occasionally eat vegetable substances, its chief food consists of fish, frogs, and tadpoles, some of which may probably be attracted within reach by mistaking the appendages on the neck for plants or animals on which they feed."[210] "There occurs at the Cape of Good Hope a harmless egg-eating Snake (Dasypeltis scabra), which flattens its head, coils as if for a spring, hisses, and darts forward as though about to strike in a way that closely resembles the characteristic mode of the Berg-Adder (Vipera atropos), of which it is mimetic. It is really quite harmless, subsisting on eggs, the shells of which are broken in the throat by the enamel-tipped processes of the vertebræ, which project into the gullet, and form the so-called gular teeth; but its resemblance both in form and behaviour to a venomous Snake presumably affords it protection from enemies."[211]

When we approach the annals of entomology,[212] we find this explanatory idea permeating the whole subject. To suggest a new instance of mimicry is considered more desirable by many than to describe a new species; while the advocates or followers of both procedures do not always seem to practise mutual admiration. The observations are not all modern. The old Swedish traveller in South Africa, Dr. Sparrmann, who first discovered (1775) the curious hemipteron, Phyllomorpha paradoxa, was impressed by its mimetic resemblance to a leaf. "At noontide I sought for shelter among the branches of a shrub from the intolerable heat of the sun. Though the air was now extremely still and calm, so as hardly to have shaken an aspen leaf, yet I thought I saw a little withered, pale, crumpled leaf, eaten as it were by caterpillars, flittering from the tree. This appeared to me so very extraordinary that I thought it worth my while suddenly to quit my verdant bower in order to contemplate it; and I could scarcely believe my eyes when I saw a live insect, in shape and colour resembling the fragment of a withered leaf, with the edges turned up and eaten away, as it were by caterpillars, and at the same time all beset with prickles. Nature, by this peculiar form, has certainly extremely well defended and concealed, as it were in a mask, this insect from birds and its other diminutive foes."[213] Canon Fowler, who has been recently writing on the Membracidæ (Homoptera), referring to the genus Sphongophorus, opines that, in some cases at all events, these forms are protective, for, when at rest, many of the insects must[214] resemble pieces of dry twigs."[215] One of the most interesting, but, to the writer, inexplicable, instances is given and figured by Dr. Gregory, as observed in Eastern Central Africa. In this case numbers of a species,—or of more than one,—of the homopterous sub-family Flatinæ (Ityraea nigrocincta) adhere to a stem, and closely resemble a flowering Transvaal plant (Sesamopteris pentaphylla). The observer adds:—"It may be that the insects were only rendered sluggish by the cold and rain, but it appears not unlikely that the members of this species have very limited powers of flight, and secured protection from birds by this ingenious mimicry of a cluster of flowers.[216] I have frequently seen other insects after heavy rain in the Transvaal follow the same habit without any protective resemblance being obtained.[217] A common orthopteron in La Plata (Rhomalea speciosa), when at rest, is "only a pretty Grasshopper; but the instant it takes wing it becomes the fac-simile of a very common Wasp of the genus Pepris."[218]

Prof. C. Emery has published, in the 'Bull. del Soc. Ent. Ital.' 1886, a short but interesting note on the habits of an Ant (Camponotus lateralis). Of this species there are two varieties—one black, like its nearest allies, the other red, with the abdomen and part of the thorax black. They live in small colonies, and make expeditions up trees to collect honeydew from the aphides. The black type (C. foveolatus, Mayr; C. ebeninus, Emery) sometimes go in troops, but generally a few join the troops of other black Ants, such as Formica gagates and Componotus æthiops. Prof. Emery suggests that, their numbers being small and their sight not very good, they find it convenient to accompany other Ants which live in larger communities, and they perhaps escape detection from the similarity of colour."[219]

Mr. Skuse considers that the Australian Hepialid moth (Leto stacyi, Scott) resembles in situ an approach to the head of a reptile of the genus Varanus. "The moth is one which passes its larval state in the butts of Eucalyptus trees for the period of five or six years, but on emergence the perfect insect is not prone to fly, and would therefore be very liable to be attacked by birds. Hence the probability that my surmise of the striking resemblance to the head of a Lizard being an instance of genuine protective imitation is correct."[220] Of the larvæ of the Hawk-Moth (Chœrocampa porcellus), it has been stated that should it "be discovered among the dead leaves, where it usually lies concealed, the first four segments are suddenly retracted, and, as in the case of C. celerio, the animal appears to have a very large head, with two glaring and dangerous-looking eyes. This transformation is no doubt of use for defensive purposes."[221] A similar observation is made on the larva of C. elpenor. "In this position its appearance is very striking, and gives a formidable look to the creature in the eyes of those animals that might have been thinking to prey upon it."[222] Poulton has proposed that these caterpillars "terrify their enemies by the suggestion of a Cobra-like serpent";[223] an hypothesis not so improbable as would appear if C. elpenor is considered a purely European species, whereas it is distributed over "Europe, Japan, Sind, Himalayas, Shillong, Nagas, Manipur";[224] and thus is found in the area inhabited by the Cobra. Dr. Gregory, in East Central Africa, relates having been "startled by a hissing noise like that of a Snake coming from a clump of grass." On closer inspection he "could just detect a small green head among the stalks, and behind this appeared, whenever the noise was repeated, an expansion like the hood of a Cobra." He subsequently found that he "had been frightened by a big Grasshopper, which, by puffing out its wings, assumed a resemblance to the shape of the head of a Hooded Snake; while its noise was a good imitation of the dull jerky hiss of some species of Snakes."[225]

But it must be remembered, as Mr. Kirby has truly remarked, that though these brightly-coloured caterpillars are probably rejected by insectivorous animals as inedible, they are not protected "against the attacks of parasites, but rather the reverse." He once bred some Tachinidæ (parasitic Diptera) from the larvæ of the Spurge Hawk-Moth.[226] Mr. Pickard Cambridge states that "upwards of a thousand parasitic grubs of the genus Microgaster have been taken from a single caterpillar."[227] The many enemies of caterpillars have been described by an Indian observer, who writes:—"Upon the whole I think birds are the least important of a caterpillar's enemies. At first, when it is so minute that a bird would not be at the trouble to pick it up, it is exposed to the cruelty and rapacity of hordes of Ants of many tribes, which scour every tree and shrub, sipping the nectar in the flowers, licking the glands at the bases of the leaves, milking the aphides, and looting and ravaging wherever they go. Besides Ants, every tree swarms with Spiders—not web-Spiders, but wolf-Spiders—which run about in quest of their prey. Then come Wasps and Ichneumons, and these, from a caterpillar point of view, are of two sorts—those which will carry him to their own quarters for the food of their children, and those which will quarter their children on him, or, I should say, in him. Finally, the few that have survived all these dangers have to run the gauntlet of the birds."[228]

Poulton refers to the two Hawk-Moths (Sesia fuciformis and S. bombyliformis), "which in some degree suggest the appearance of Humble-Bees," as instances of "mimicry of Hymenoptera by Lepidoptera." But when he offered a living specimen to a Lizard (Lacerta muralis), the animal was "not imposed upon in the least, but devoured the insect without hesitation or caution. Although Humble-Bees are eaten by Lizards, they are always seized cautiously, and disabled before being swallowed."[229] This certainly seems to be very negative evidence. The well-known British Moth, Lasiocampa quercifolia, affects a resting position which "makes it appear exactly like a dead leaf. One is walking along, maybe, when his attention is attracted to a dead brown leaf hanging on a blackthorn bush, suspended by a slender stalk, and swaying to and fro in the air with every passing breeze. You feel satisfied it can be nothing but a rich purplish-brown leaf, and yet your trained eye is hardly satisfied; and as you slowly take in the outline, and put your finger beneath the supposed stalk of the leaf, another slender stalk is gradually pushed up, and a Lappet Moth dangles from your finger.'[230] Here the expression "trained eye" of the entomologist would suggest a more developed "trained eye" of the moth's natural enemies, and hence any theory of protective mimicry is much discounted. Should such a theory be advanced, the instance would probably be more applicable to conscious or active mimicry, to be discussed later on. The same author gives a subsequent illustration which seems capable of the same comment. Another of our moths (Orgyia antiqua) has an apterous female, and in this condition, "seated on her cocoon after emergence, she looks so exactly like a Spider that only practical entomologists recognize her; she lays her eggs on the web, and never stirs."[231] Dr. Sharp has remarked on the eggs of Phasmidæ that nearly everyone who mentions them speaks of their extreme resemblance to seeds. "Goldie has suggested that this is for the purpose of deceiving Ichneumons; it is, however, on record that the eggs are actually destroyed by Ichneumons." Not only do the eggs have a history like that of seeds, and resemble them in appearance, but their capsule, in minute structure, greatly resembles vegetable tissue.[232] Again he states:—"The egg of a Phasmid has not only a general resemblance in size, shape, colour, and external texture to a seed, but the anatomical characters of certain seeds are reproduced on the external surface, there being a hilar area, a hilar scar, and a capitulum corresponding to the micropylar caruncle of such seeds as those of the castor-oil plant (Ricinus communis)."[233] The eggs of Phyllium crurifolium are a case in point. Henneguy states "that a prominent lozenge on the egg represents the surface by which the achene of an umbelliferous plant is united to the column, and that the micropyles are placed on this lozenge. As regards the egg-capsule, the same writer observes:—"Almost every botanist, on examining for the first time a section of this capsule, would declare that he is looking at a vegetable preparation."[234]

In Plant-life the same suggestions occur. The bladderworts (Utriculariæ) are carnivorous, and capture small crustaceans, larvæ of gnats, &c, by the aid of small bladders with orifices closed in each case by a valve, which permits objects to penetrate into the cavity of the bladder, but not to issue out of it. "The bladders of Utriculariæ, living in still water, look delusively like certain Ostracoda, especially species of the genus Daphnia. The bladder itself resembles the shell-covered body in size and form, and the bristles the antennæ and swimmerets of one of these crustaceans."[235] Small crustaceans are probably thus allured to their own destruction, and the bladderworts exhibit "aggressive mimicry." In the 'Botanical Gazette' for April, 1896, an interesting case ascribed to mimicry is described. The seeds of the "Philippine Island bean, from the coast near Manila, so closely resemble the quartz pebbles among which they fall, in shape, size, colour, lustre, hardness, and stratification, as to be indistinguishable from them except by a very close examination."[236]

Sometimes we read accounts of assimilative colouration, where it is difficult to see the raison d'être, if mimicry is propounded. Such an instance is given by Mr. Nicholas Pike:—"On my first visit to Round Island" (near Mauritius), "I captured a Scorpion of a bright green, just the colour of the leaves of the Jubæa palm it was disporting on. The creature was very active and defiant, and it was with difficulty I caught him."[237]

As proving the great caution which is necessary before dogmatically asserting anything more than "suggested or probable mimicry" with reference to the preceding instances of simulative resemblances in animals and plants, it may be well to record some cases of what may be considered as

 

Suggestive but Disputed or Mistaken Mimicry.

Prof. Semper, when staying in the Balearic Islands, found among the polypes of a coral (Cladocora cæspitosa) Annelids belonging to the genus Myxicola, which lived in long mucilaginous tubes which they had formed in the rifts of the coral. "As long as no light was thrown upon them they protruded themselves just so far as that the top rim of the corona of tentacles was on a level with the tentacles of the polyps, so that the worm and the polyps were both extended; the coral itself presented a perfectly level surface of cups. Moreover, the funnels of Myxicola were of precisely the same chocolate-brown colour as the polyps; and, when fully extended, the interior of the funnel formed by the tentacles looked exactly like the oval disc of one of the neighbouring polyps, for the radial pinnules were in the same position as those lines which, on the oval disc of the polyp, radiate towards the narrow central oval slit; in the Myxicola a small central slit was observable, and all the parts which corresponded so exactly in size and position also displayed exactly the same colouring of greenish grey, with radial lines of a lighter hue and a narrow white streak in the middle. In short, the resemblance in size, position, and colour of every part of the two creatures was so perfect that for a long time I took the corona of the Annelid for a polyp, until, by an accidental blow, I caused all the Myxicolæ of a large coral-stock to shrink suddenly into their tubes, though it was not severe enough to induce an equally rapid movement in the polyps of the apathetic Cladocora." At the time the Professor "felt an almost childish delight at having detected so flagrant an instance of protective mimicry" but soon found reason to doubt this interpretation of the facts. He subsequently found a marine Sponge in which hundreds of this same Myxicola were living, but the Sponge was coloured very differently from the Annelida, so that no protection was offered. Seeking it in other spots, he found the Myxicola almost everywhere, "on the rifts of rocks and in the sand, between marine plants, or the tubes of other worms"; and, whenever he examined it closely, "it was exactly of the size and colour of the polyps of Cladocora cæspitosa." As Prof. Semper concludes, "Mimicry, it is plain, is out of the question; the resemblance between the two creatures is simply and wholly accidental."[238] The second illustration is from the pen of Mr. Trimen, so well known for his entomological advocacy of the claims of mimicry, and who describes a most remarkable instance which came to his notice in connection with the pupa of Papilio lyæus. He received from a correspondent a small box containing what he took at the first glance for three ordinary green chrysalids of that butterfly. Only one of these objects, however, was a veritable chrysalis, the two others being the seedcapsules of a plant stated to be a species of Hakea. "The tint of green, the general lateral outline (especially the bulging ventral convexity of the wing-covers), the projections of the bifid head, the attenuated form of the posterior abdomen and anal extremity, and even the slight ferruginous tips of the projections of the head, are all reproduced in the seed-capsules to a very deceptive extent." The chrysalis was found "in the neighbourhood of a hedge of the Hakea, and if this plant had been a native of South Africa it can scarcely be questioned that a strong case of mimicry would readily have been admitted by observers. As a recent introduction from Australia, however, it is clear that Hakea cannot have been the model for the pupa of a Papilio of a specially African group."[239] Mr. Belt, so well known for his excellent observations in support of mimicry, gives us another warning against guessing conclusions. "Ant-like Spiders have been noticed throughout Tropical America, and also in Africa. The use that the deceptive resemblance is to them has been explained to be the facility it affords them for approaching Ants, on which they prey. I am convinced that this explanation is incorrect so far as the Central American species are concerned. Ants, and especially the stinging species, are, so far as my experience goes, not preyed upon by any other insects. No disguise need be adopted to approach them, as they are so bold that they are more likely to attack the Spider than a Spider them. Neither have they wings to escape by flying, and generally go in large bodies easily found and approached." Mr. Belt, however, concludes that the Spider is thus protected against the attacks of small insectivorous birds.[240] Subsequently, however, Mr. Herbert H. Smith has reaffirmed what Mr. Belt denied—"the Spiders eat the Ants," and "they eat the particular Ants which they mimic. At all events, we verify this fact in a great number of cases, and we never find the Spiders eating any but the mimicked species."[241] Dr. Scharff thinks "that the colours of Slugs in Ireland are at all ages, as a rule, protective";[242] while Mr. Adams is inclined to think "that climate may be a factor in the matter." He has "taken more brilliant forms, and those more abundantly in the South of England (where the climate is warmer), than in the North." Again, "all along the south coasts of England and Wales, Cardigan Bay, and the west coast of the Isle of Man, and the north coast of Ireland (all of which are noted for a mild climate), I have taken coloured forms abundantly; while on the coasts of Lancashire and North Wales, and the east coast of England from the Thames to the Tees (where the climate is more bracing), I have no personal records for anything but the type."[243]

In plant-life such resemblances are not uncommon. In parasitic fungi "the fructification of Polyporus betulinus strongly resembles the whitish bark of the birch, and that of P. fomentarius, parasitic on old beech trees, exhibits the same pale grey as does the trunk of a beech."[244] There is a butterfly common in certain parts of the Argentine which Dr. Seitz at first mistook for the European Vanessa (Araschnia) levana, so closely does it resemble that butterfly in colour, in the notching of the wings, and in other ways. Moreover, there is a variety of this form which is in the same way exceedingly like the form prorsa. A closer examination of the insect showed that it did not belong to this species at all, or even to the same genus; it is a member of another genus, Phyciodes. "If," says Dr. Seitz, "these were found in our country, no one would doubt that this was a case of mimicry as perfect as any which exists." It might be suggested that it is a case of mimicry, but the mimicking and mimicked forms have each gone their own way, one migrating to one country, and one to another; they might possibly at one time have both lived in North America, and later on separated, one going south and the other east, crossing over into Asia by way of Behring's Strait. Such an explanation would be, as Dr. Seitz points out, entirely contrary to what is known of the distribution of these insects; for the genus Araschnia is absolutely confined to the Old World, and Phyciodes to the New World.[245] Of course it may be contended that the case does not apply, as it is an integral axiom in the theory of mimicry that the mimicker and the mimicked must, and are, always found together in the same part of the world, or that one of them may have become extinct. But here we see the phenomenon can be observed in widely separated habitats, and in birds one cannot help being amazed at the great superficial resemblance between the Secretary Vulture (Serpentarius secretarius) of South Africa, and the Brazilian Seriema (Cariama cristata).

Mr. J.H. Gurney has given twenty cases, "On the tendency in Birds to resemble other Species":—"On three occasions adult males of our British Sparrow-Hawk (Accipiter nisus) have been shot in this country, which so far resembled the South African (A. rufiventris, Smith) as to have the breast and under parts a clear rufous without any transverse bands (cf. 'Ibis,' 1893, p. 346). Buzzards which were indistinguishable from the rufous North African Buzzard (Buteo desertorum) have been killed in England three or four times (cf. 'Ibis,' 1889, p. 574).... In 1861 an example of Picus major, our Greater Spotted Woodpecker, obtained in Shetland, varied so as a little to resemble P. leuconotus, the White-backed Woodpecker, and was even figured as such in Gould's 'Birds of Great Britain.'... Snipes have twice been shot which presented some of the characters of the American Gallinago wilsoni."[246]

In Southern Africa the Anhinga (Plotus levaillanti, Licht.) affords a mimicry which is apparently purposeless. Le Vaillant himself, its discoverer, states:—"Indeed, there is no person who, upon seeing the head and neck only of an Anhinga, while the rest of the body is hid among the foliage of the tree on which it is perched, would not take it for one of those serpents accustomed to climb and reside in trees, and the mistake is so much the easier, as all its tortuous motions singularly favour the illusion."[247] This bird swims so low in the water that only its neck is to be seen; and, from observations in Natal, Mr. Ayres says that "in this position the bird might easily be taken, by those unacquainted with it, for a Water-snake."[248]

According to Dr. Bowdler Sharpe, one of the most interesting of all birds is the Common Cuckoo (Cuculus canorus), not the least remarkable feature in its conformation being its great similarity to a Hawk, as not only shown by its colour and form, but also by its mode of flight, and which is so marked that the bird is always mobbed by smaller birds, as if it was really a Hawk.[249] Jefferies, who excelled as an observer, was clearly not of this opinion, and he thus writes on the subject:—"The Cuckoo flies so much like the Hawk, and so resembles it, as at the first glance to be barely distinguishable; but on watching more closely it will be seen that the Cuckoo flies straight and level, with a gentle fluttering of the wings, which never seem to come forward; so that in outline he resembles a crescent, the convex side in front. His tail appears longer in proportion, and more pointed; his flight is like that of a very large Swallow flying straight."[250] Again he remarks that birds "will pursue a Cuckoo exactly as they will a Hawk," but adds:—"I will not say that that is because they mistake it for a Hawk, for the longer I observe the more I am convinced that birds and animals often act from causes quite distinct from those which at first sight appears sufficient to account for their motions."[251] The dread experienced by small birds for their larger brethren of prey is probably open to qualification, for Gilbert White tells us of a Swallow who "built its nest on the wings and body of an Owl that happened by accident to hang dead and dry from the rafters of a barn."[252]

As with "mimicry," so the theory of "warning colours" may be hastily predicated. Among Flatworms in the terricolous Triclads or Land Planarians, some species "are frequently banded or striped with brilliant colours. Geoplana cærulea, Mos., has a blue ventral surface, and is olive-green or dark Prussian blue above. G. splendens, Dendy, is marked dorsally by three stripes of emerald-green alternating with four dark brown longitudinal bands. The mode of colouration, though somewhat variable, is an important specific character. Its significance, however, is not clearly understood. The colours may be a warning signal, as some Geoplana at least are disagreeable to the taste of man and some birds; but since Land Planarians are largely nocturnal animals, living by day under logs, banana-leaves, and in other moist and dark situations, this explanation is clearly insufficient."[253] Among the Polychaete Worms the same caution is necessary. "Carnivorous forms like Amphinomids and Syllids present as wide a range of tint as the limnivorous forms, like Cirratulus, Sabella, or Maldanids. Shore-lovers and deep-sea dwellers and surface-swimmers all exhibit equally bright or equally sombre tints; it is therefore difficult and rash to dogmatise on the 'use' of these colourings to these animals, or to point to this worm as being protectively, to the other as being warningly, coloured; for we are too ignorant as to the habits of the worms."[254]

As we record instances of what appear only capable of being ascribed to "suggestive but mistaken mimicry," we meet with natural resemblances which seem to fall under a category of
 

Purposeless Mimicry.

Some orchids have a curious resemblance to insects, after which they have accordingly been named the Bee-orchis, Fly-orchis, Butterfly-orchis, &c, but it has not yet been satisfactorily shown what advantage the resemblance is to the plant.[255] The fungi, known by the name of club-tops, much-branched, flesh-coloured, yellow or white Clavariæ, which often adorn whole tracts of ground in a wood, imitate the structure of corals; Hydneæ are like Sea-urchins, and Geaster like a Starfish, whilst the various species of Tremella, Exidia, and Guepinia, which are flesh-pink, orange, or brownish in colour, and the white translucent Tremellodon gelatinosum, resemble gelatinous Sponges. The small stiff Toadstools (Marasmius) which raise their slender stalks on fallen pine-needles, remind one of the rigid Acetabulariæ. Other Toadstools, with flat or convex caps exhibiting concentric bands and stripes, such as the different species of Craterellus, have an appearance similar to the salt-water alga known by the name of Padina. Dark species of Geoglossum imitate the brown Fucoideæ; and one may fancy the red warts of Lycogala epidendron, a plasmoid fungus inhabiting the rotten wood of dead weather-beaten trees, to be red Sea-anemones with their tentacles drawn in, clinging to grey rocks. However farfetched this comparision between the two localities may seem at first sight, everyone who has had an opportunity of thoroughly observing the characteristic forms of vegetable and animal life in woods, and at the bottom of the sea, will inevitably be convinced of its accuracy.[256] Again, in primitive plant life (Thallophyta), in the family Caulerpaceæ, "the genus Caulerpa contains nearly one hundred species, which present the most varied external forms, simulating those of many of the higher plants, such as Mosses, Ferns, Mare's-tails, Cactuses, Conifers, &c."[257] It has been suggested that some of the seeds of Euphorbiaceæ, notably those of the Castor-oil plant (Ricinus), resemble beetles, and, as such, may be mistaken by birds and carried a small distance before being dropped. This seems very doubtful. Ricinus seeds and those of Para Rubber (Hevea braziliensis), which resemble them on a large scale, are ejected explosively from their capsules to a distance quite sufficient for their dispersal, and falling, as they constantly do, among the herbage, would certainly escape most insect-eating birds.[258]

Fishes of the family Pomacentridæ, belonging to the spiny-finned division, which frequent the neighbourhood of coral reefs and islands, and thus closely resemble the scaly-finned fishes, Chætodonts, in their mode of life, also are very similarly and beautifully coloured. But in the opinion of Dr. Günther this is one of many instances showing that the colouration is due to a great extent to "the agencies of climate, of the surroundings, and of the habits of animals."[259]

 

Active Mimicry.

Another and very important distinction to be drawn when dealing with instances of mimicry and protective resemblance is one long since pointed out by Kirby and Spence, and one that demands the utmost consideration. To use the words of the teleological authors of the immortal 'Introduction to Entomology,' there are Passive means of defence, such as are independent of any efforts of the insect; and Active means of defence, such as result from certain efforts of the insect, in the employment of those instincts and instruments with which Providence has furnished it for this purpose.[260] Thus, in a little book on British Hawk Moths, the writer states that some of these insects "seem to put all their trust in a resemblance they may bear to some natural object, which by a wonderful and unerring instinct they seldom fail to find."[261] Many of the illustrations given by authors of protective resemblances and mimicry are "passive," and considered as the result of natural selection, slowly accentuating and perpetuating the current of variation that makes for protection, and of which, on every philosophical consideration, the animal thus evolved can have no consciousness, beyond a more or less habit of adaptation to its environment; in fact, a Cartesian would say the whole phenomenon was indicative of animal automatism. But it is open to strong suggestion that this is only one, and a subordinate phase of the phenomenon, and that animals of their own volition, and in their efforts to avoid their enemies, place themselves where possible in such adaptation to their surroundings, that protective resemblance and some forms of mimicry are due to animal intelligence, and not so entirely to what is generally understood as the unconscious process of natural selection.[262] Mr. Coe has also affirmed that "there is an enormous amount of evidence, which shows that animals are conscious of the protection afforded by colour, and that they assist the 'disguises' which arise from their likeness to inanimate objects by their own intelligence and contrivance."[263] Thus Mr. Wakefield Richardson has recently recorded an observation he made by which a Wren supplied the insect food required for her young by carrying the excrements of the nestlings, as is the habit of some birds, and placing them with great care on different parts of a thorn bush.

"Apparently she had placed them thus to attract the flies, for each time she alighted on the bush she visited several, picking off the flies until she had enough to take back to her young."[264] This may surely be taken as an instance of aggressive mimicry, consciously or actively pursued. According to Mr. Matthias Dunn, "Some fishes have such power over their own appearance that when they like they can change the colour of their skin in keeping with their surroundings. I have seen Surmullets, when going from the brown sand to the dark rocks, quickly change from one colour to the other, and I know of about forty other fishes which can do the like in more or less time."[265] On this statement a writer has recorded that, in 1898 in the Aquarium at Concarneau, in Brittany, Turbot were seen "that gradually assumed the colour of the sand in which they were placed; so much so that it required a very keen eye to detect them lying at the bottom of the tank."[266] Another writer has more recently remarked, in discussing "the beautiful and protective resemblance" which some insects "bear to their surroundings," that there can be no doubt that such species "possess an inherited and instinctive knowledge of this assimilation, and select such places as a protection against their natural enemies."[267] Of course the suggestion of active mimicry must not be made too absolute. Thus Mr. Storrs Fox has proposed a very reasonable hypothesis that supposing certain caterpillars not very particular as to their food, either Elm, Lime, Birch, &c, and further assuming that such caterpillars were more easily overlooked on Birch by resembling the catkins of that tree, then those broods which fed on trees other than Birch would be most likely to be devoured by enemies, and so gradually a race would grow up which invariably fed on Birch.[268]

The active mimicry here discussed does not deal with the mimicking by birds of the songs of their fellows. This imitative faculty had been recorded of birds in captivity by Aristotle. But in a state of nature the same thing occurs. Mr. Butterfield has narrated his having heard a Whinchat, a bird of no extensive vocal capacity, imitate "in quick succession the song of the Wren, Song Thrush, Chaffinch, Corn Bunting, Tree Pipit, Greenfinch, and Starling."[269] Mr. Riley Fortune has known the Starling to give perfect imitation of the cries of the Sparrow, Lapwing, Golden Plover, Chaffinch, Blackbird, Yellowhammer, Thrush, Jackdaw, Swallow, and many other birds.[270] Prof. Lloyd Morgan is of opinion that "mimetic activities are due to a mimetic impulse. Some of them are probably involuntary and due to connate impulse; but others are certainly due to intelligent imitation."[271] Thus Lumholtz, in Queensland, observed the mental process in the Lotus-bird (Parra gallinacea): "The grown bird is not shy, but the young are extremely timid. I had once or twice seen the old birds with young, but as soon as I approached them the young always disappeared, while the old birds walked about fearlessly, as if there was no danger. It long remained a mystery to me how they could conceal themselves so well and so long, but one day the problem was solved. An old bird came walking with two young ones near shore. I hid behind a tree and let them come close to me. As I suddenly made my appearance, the small ones dived under the water and held themselves fast to the bottom, while I watched them for a quarter of an hour before taking them up."[272] The difficulty in cognizing the phenomenon of active mimicry is no greater than that experienced in endeavouring to explain the derivation, or evolution, of active means of defence, in fact it is much less formidable; for it is easy to comprehend even from our own experience that concealment is frequently a need, and is an art capable of cultivation and improvement. But many of the means of animal defence are in themselves almost inscrutable; we see the weapon used, but cannot account for its present existence. Natural selection may explain the improvement and survival of such useful organs, but their origin is still obscure. We will briefly allude to a few in order to make our comparison clear. The Horned Lizard (Phrynosoma sp.), commonly known as the "Californian Toad," possesses the power of ejecting jets of blood from the eyes, apparently as a means of defence. The Sand Shrimp (Crangon vulgaris) can suddenly raise a perfect cloud of fine sand round itself—"firing, so to speak, a 'broadside for the sake of the smoke,' and literally throwing dust in the eyes of his enemies."[273] The well-known instance of the "Cuttle-fish," which is able to discharge its inky secretion, and escape, like a diplomatist, in the darkness thus effected, is another illustration, as is also the Bombardier Beetle (Pheropsophus sp.), which when caught explodes its abdominal artillery, producing sound, smoke, and pain alike. The larva of the Puss Moth (Cerura vinula) can squirt a fluid—formic acid—when handled.[274] The common Partridge will "feign itself wounded and run along the ground fluttering and crying before either dog or man, to draw them away from its helpless unfledged young ones."[275] Sometimes the indications of intelligent action may be almost inappreciable to our untrained cognitions in animal psychology, but even then the loosely used, and still more vaguely understood term, instinct, would have to be applied. At other times volition seems to be influenced by environment. Humboldt relates that "in the Missions of the Orinoco, and on the banks of the river Amazon, the Indians who catch Monkeys to sell them, know very well that they can easily succeed in taming those which inhabit certain islands; while Monkeys of the same species, caught on the neighbouring continent, die of terror or rage when they find themselves in the power of man. The Crocodiles of one lake in the llanos are cowardly, and flee even when in the water; whilst those of another lake will attack with extreme intrepidity. It would be difficult to explain this difference of disposition and habits by the mere aspect of the respective localities. The Sharks of the port of La Guayra seem to furnish an analogous example. They are dangerous and bloodthirsty at the island opposite the coast of Caracas, at the Roques, at Bonayre, and at Curassao; while they forbear to attack persons swimming in the ports of La Guayra and Santa Martha."[276] According to Hudson, the Puma possesses "a unique instinct of friendliness for man," though it violently attacks other large Carnivora, and is, within the tropics, "a great hunter and eater of Monkeys, which of all animals most resemble men."[277] Another instance is the "dying-places" of the Guanaco (Lama guanacus) at the southern extremity of Patagonia, as recorded by Darwin, Fitzroy, and Hudson. That young Haddock should frequent deep water, and the young Cod seek the inshore water, "is one of those mysteries it is difficult to unravel."[278] The Apron (Aspro vulgaris), a freshwater fish belonging to the family Percidæ, according to Prof. Seeley, "lives at the bottom, and comes to the surface only in bad weather with a north or west wind, when other fishes take refuge at the bottom."[279]

Many actions of animals of a peculiar, constant, and distinctive character seem quite purposeless. This is particularly striking in the account given of the habits of the two species of African Rhinoceros (R. simus and R. bicornis). The calf of R. simus "always runs in front of the cow, while the calf of R. bicornis invariably follows its mother; this habit never varies." Again, R. bicornis, after dropping its dung, "proceeds to stamp upon the dung and to tear and dig up the ground in the immediate vicinity, so that there is absolutely no chance of anyone missing the place where a R. bicornis has spent the day. R. simus, however, leaves his dung alone, and does not trample and scatter it about; moreover, he is conservative in these matters; he always drops his dung in one place until he has raised a huge heap, then he starts the same operation in another place, and so on."[280] In Patagonia, the Guanaco has somewhat similar habits. Cunningham writes:—"Darwin has commented on the singular habit which they possess of depositing their droppings on successive days in the same defined heap, and this I have likewise frequently observed."[281] According to Romanes, "The dusting over of their excrements by certain freely roaming carnivora; the choice by certain herbivora of particular places on which to void their urine, or in which to die; the howling of Wolves at the moon; purring of Cats, &c, under pleasurable emotions; and sundry other hereditary actions of the same apparently unmeaning kind, all admit of being readily accounted for as useless habits originally acquired in various ways, and afterwards perpetuated by heredity, because not sufficiently deleterious to have been stamped out by natural selection."[282]

(To be continued.)

 

 

THE ZOOLOGIST

 

 

No. 702.— December, 1899.

 

 

BIOLOGICAL SUGGESTIONS.
MIMICRY.

By W.L. Distant.

(Continued from p. 470.)

 

To revert to "active mimicry,"[283] and to render our signification of the term as clear as possible, we will first adduce an instance given by that competent lepidopterist, Georg Semper:—"During the last ten years the well-known white-leaved variety of Acer negundo has been largely planted in gardens in Hamburg, and since this the common White Cabbage Butterfly has accustomed itself to settle by preference on this shrub. It is then extremely difficult to distinguish the butterflies as they sit on the leaves, their yellowish colour being lost in that of the leaves."[284] Had Hamburg been a locality in some terra incognita, and visited by a travelling naturalist of observing faculties, who can doubt—and why should surprise be felt under the circumstances—that this observation would have appeared, and been recorded, as an instance of passive mimicry? A similar observation was communicated to Mr. Trimen by Mrs. Barber. She was impressed by the behaviour of a male of the conspicuous butterfly, Papilio cenea, which twice deliberately selected in her garden, as a resting place during a shower of rain, a shrub whose pale yellow and brown seeds and flowers entirely agreed with the colouring of the under side of its wings.[285] Of butterflies belonging to the Tropical American genus Siderone, Mr. Dent states:—"They always rest with wings folded over their bodies on branchlets, the markings and colouring of the under side of the wings resembling exactly dry brown or yellow leaves."[286] Mr. Cornish has written:—"Many of the small blue British butterflies have greyish spotted backs to their wings. At night they fly regularly to sheltered corners on the chalk downs where they live, alight head downwards on the tops of the grasses which there flourish, and, closing and lowering their wings as far as possible, look exactly like a seed-head on the grasses."[287] Mr. Carrington noticed for several evenings that a large White Cabbage Butterfly (Pieris brassicæ) searched out a few "sportive" whitish or creamcoloured leaves of a variety of ivy, and roosted upon one for the night.[288] Mr. Trimen has observed the Satyrid butterfly Melanitis leda, which "rests among dead leaves on the ground in shady places, and is then indistinguishable from them"; and a parallel case, and a similar effect, is produced by the female Eronia leda, which settles on the faded bright yellow leaves of the Erythrina tree."[289] Our well-known Orange-tip Butterfly (Euchloë cardamines), as observed by Mr. T.W. Wood towards evening or in cloudy weather, may be found at rest on the tops of grass or flowers, but more particularly on Anthriscus sylvestris, and almost always near that plant; the chequered white and green alone visible when the insect is at rest assimilates with the white flowers of the Anthriscus as seen against the green background.[290] Attention has recently been called to what appears to be more or less active mimicry in two small British moths. Penthina gentianana, in its larval condition, feeds on the pith of the receptacle in teasel-heads, seed-heads of Dipsacus sylvestris; while another moth (Eupœcilia roseana) feeds on the seeds themselves. "The habit of P. gentianana on its emergence is to sit with head buried between the spinous scales of the receptacle, and with the posterior portion of its wings projecting a little beyond them. Roughly divided (as the insect is into a light upper and a dark lower part), its resemblance when in this position to a bird's excrement is very noticeable. If a number of teasel-heads be examined, it will be found that in some instances the inner part of the seeds—i.e. that part which is in contact with adjacent seeds—assumes a bright pink colour. Now, E. roseana has a very frequent habit of sitting lengthways along the spines of the scales above referred to, and here again the resemblance of the insect, with its colouring of rosy pink shading into yellow, to a partly displaced seed is worthy of notice."[291] One of the strongest illustrations of protective mimicry by a butterfly, and one of the most widely known—for who has not read Wallace's 'Malay Archipelago'?—is afforded by leaf-butterflies of the genus Kallima. But, as Mr. Badenoch has well enquired, "Of what avail would be the disguise were the insect prone to settle upon a flower, or green leaf, or other inappropriate surface?"[292] The partiality of this insect for settling on dry and withered leaves appears a true instance of active mimicry. The idea of some conscious volition in the protective habits of this butterfly is supported by remarks made by the Indian naturalist who writes under the name of "Eha":—"They see a little better in front of them, and I have noticed that the leaf-butterfly always alights head downwards, so as to face anything coming up the tree, which is much the most likely direction of assault from a Lizard. (In pictures generally, and in the show-case at the British Museum (Nat. Hist.), the butterfly is turned the opposite way, facing upwards, which is no doubt more appropriate to its character as a leaf; but that is a detail rather above the intelligence of a Lizard: at any rate, I never saw a Kallima sit in that position.)"[293] The well-known Tropical American butterflies belonging to the genus Ageronia, which flatten their similarly coloured wings on the lichen-covered trunks, are also described as to "invariably rest head downwards."[294] Mr. Geo. Windsor Earl relates that at Sourabaya he saw Lizards attack large moths, but they were not always successful, "unless they could manage to seize the head, when, after a struggle of a few minutes, the little reptile would bear away his prey to devour at his leisure."[295] Weismann seems more or less of this opinion also, for he observes:—"These markings are composed of two parts, the upper of which is on the fore wings, while the lower one is on the hind wings. The butterfly when at rest must therefore keep the wings in such a position that the two parts of each marking exactly correspond, for otherwise the character would be valueless; and, as a matter of fact, the wings are held in the approximate position, although the butterfly is, of course, unconscious of what it is doing. Hence a mechanism must exist in the insect's brain which compels it to assume this attitude, and it is clear that the mechanism cannot have been developed before the peculiar manner of holding the wings became advantageous to the butterfly, viz. before the similarity to a leaf had made its first appearance."[296] We should opine, however, that the Kallima is exercising some volition in seeking the environment of the withered leaves with which the under surface of its wings approximate, an action we have seen pursued by other butterflies with reference to different surroundings, and that the exact corresponding position of the wings is hereditary, and perhaps now describable as unconscious cerebration, or reflex action. Animals do not all use the same means for protection; the method may be different, but the purpose is similar. Thus Partridges "roost close to the ground, and sleep with their heads tucked close together. A covey in this position represents little more than a mass of feathers. They always spend their nights in the open, for protective reasons. Birds which do not perch would soon be extinct as a species were they to seek the protection of woods and hedgebottoms by night. Such ground generally affords cover to vermin—Weasels, Polecats, and Stoats."[297]

An active or aggressive mimicry is probably the explanation of the observation recorded by Mr. Woodford, made on Peel Island, Moreton Bay, where in the yellow-and-white blooms of different shrubs he found Spiders which were practically concealed by their assimilative colouration to these flowers. They were seen to attack the Bees which visited the bloom.[298] M.E. Heckel, of Marseilles, has described an interesting case, which may be frequently seen in the South of France. The Spider, Thomisus onustus, is often found in the flowers of Convolvulus arvensis, where it hides itself for the purpose of snaring two Diptera, Nomioides minutissimus and Melithreptus origani, on which it feeds. Convolvulus is abundant, and three principal colour variations are met with—there is a white form, a pink one with deep pink spots, and a light pink form with a slight greenishness on the external wall of the corolla. Each of these forms is particularly visited by one of three varieties of Thomisus. The variety which visits the greenish form has a green hue, and keeps on the greener part of the corolla; that which lives in the white form is white, with a faint blue cross on the abdomen, and some blue at the end of the legs; the variety which lives in the pink form is pink itself on the prominent parts of the abdomen and legs. The colour, however, is of an assimilative nature, as M. Heckel found that when the pink, white, green, and yellow varieties of the Spider are confined together in a box they all become nearly white.[299]

That undoubted examples of active mimicry are to be found among the Arthropoda will occur to the mind of every naturalist at the mention of "Trap-door Spiders." It is unnecessary to quote here all the observations made by competent and veracious authorities as to the beautiful adaptations effected by these Spiders, by which the lid or door of their burrows is made to perfectly assimilate with the surrounding surface. Gillies, describing the habits of a New Zealand species, writes:—"The evidences of thought, ingenuity, and reason are displayed in the selection of the particular materials used in special places; in the calculation of the probabilities of certain contingencies happening; and in the apparently careless arrangement of both living and dead matter, so as to make what is in reality the highest art appear to be the result of natural and ordinary circumstances." In some cases there is "a plant of green grass.... planted artificially, and growing on the lid." In other cases "you will find clay on the outside of the lid, plastered and smooth, or possibly with an imitation crack, introduced apparently at random." In others, again, "the skilful artist brings to his aid all the taste and knowledge of the practical gardener—selects plants suited for his purpose, brings them from a distance, and actually transplants them to the top of his trap-door with astonishingly natural variety and arrangement"; or "you will find mosses of various hues and colours growing green, and sometimes brown and dead, upon the lid"; or sometimes "this tiny pasture is brilliantly ornamented with parti-coloured patches of lichens," or "sprigs of lycopods, ferns or heaths, veronicas, and whiteberry plants are introduced to correspond with the bolder herbage around"; or, "if the common white tussock is the prevailing vegetation in the locality, ... the dead bits (of that kind) of grass are woven adroitly into the trap-door or round its mouth, so as to deceive the most practised eye," &c.[300] Moggridge found a nest in a plant which had been brought to him which was quite covered on the surface with moss, and the moss grew on the surface of the door itself, and looked exactly like that growing all round.[301] Livingstone describes a nest of which "the outside looks exactly like the surrounding surface of the ground, so that when the door is shut it is impossible to find the nest. The hole can therefore only be seen when the inhabitant has gone out and has left the door open behind it."[302] It may be contended that this shows only mimicry in the habitation, and not in the appearance of the animal itself; or, again, that "aggressive" rather than "active" should be the qualitative term applied to this mimicry; but we can refer to instances where animals disguise their own bodies in a similar manner, and with a like intelligence, to these Spiders. The little Æsop's Prawns (Hippolyte (virbius) varians, Leach, and H. fascigera, Gosse) may perhaps be cited as practisers of active mimicry. Prof. Herdman, in 1893, described four variations of H. varians, each agreeing in hue with the colour of its special habitat,[303] and was inclined to accept the fourth possibility of explanation which he suggested, viz. "The young may be very variable in tint, and then, by the action of natural selection, such as do not agree in hue with the surroundings will be eliminated." Mr. James Hornell, at the Jersey Biological Station, has made a further series of experiments with these species, and has accepted the third postulate of Prof. Herdman, viz. the "adaptability may be retained throughout the rest of their lives, and the adults may change hue upon change of environment." Mr. Hornell found that a pale olive-brown H. varians taken from amid similarly coloured seaweed became of a vivid green within an hour when placed with Enteromorpha, and the same specimen changed to a pinkish red within three hours when placed amid Delesseria. Again, red-coloured specimens of the same species from amongst tufts of red weeds changed to green during a single night when placed with Enteromorpha, or with Cladophora, and back again to red within four hours when placed once more amid red weed. This change of hue took place as rapidly in the dark as in the light. The weeds affected by the smooth-skinned H. varians, in the great majority of cases, are smooth in surface, and not overgrown with foreign matter. "In marked contrast, the body of H. fascigera is ornamented with tufts of brush-like hairs, and if a spray of the coarse Corallina, where this species makes its home, is examined, the stems are found covered with a multitude of abodes of tiny "messmates," porcelain-like coils of the little tube-worm Spirobis, dull-looking cylinders tenanted by that lovely miniature Sabeliid, Othonia gracilis, and crusting colonies of Bryozoa protruding ever and anon circlets of hair-like tentacles." Hence, when the hairy H. fascigera is at rest on such a weed, the mimetic adaptation is greatly accentuated.[304] Thus also the connection of the small Short-tailed Crab (Nautilograpsus minutus), which swarms on the Gulf-weed, and assimilates in colour thereto. Sir John Murray, during the voyage of the 'Challenger,' studied the habits of these Crabs. He observed "that, although every floating thing upon the surface is covered with them, they are rarely met with swimming free, and that whenever they are dislodged and removed a little way from their resting place they immediately make the most vigorous efforts to regain it."[305] The Common Shrimp (Crangon vulgaris), when suspecting danger, "sinks upon the sand, and, setting his swimming-feet rapidly to work, they 'kick up such a dust' in the water that he is hidden in a cloud of fine sand, which as quickly settles down and partially buries him—sufficiently so with his sandy hue to effectually hide him."[306] Mr. W.A. Lloyd has described a somewhat similar habit of the Echinus or Sea-urchin. "Its chief delight, when in an aquarium, appears to be to cover itself with pebbles, which it picks up with its spines. At first I imagined that the little stones had fallen by mistake, and, wishing to do all in my power to render my captive happy, I removed the pebbles with a brush; but the Sea-urchin evidently did not appreciate my would-be kindness, for in a short space of time he had again covered himself with pebbles; and so completely was he hidden beneath them, that if he had not crawled up the side of the aquarium with his load I should have had some difficulty in discovering his whereabouts."[307] Some species of Crabs, such as Maja verrucosa, Pisa tetradon and P. armata, Inachus scorpioides, and Stenorrhynchus longirostris, cut off bits of Wracks, Florideæ, Ulvæ, &c, with their claws, and place them on the top of their carapaces, securing them on peculiar spiky or hooked hairs. The fragments grow firmly to the Crabs' chitinous coats, and, far from being harmful to the animals, are, on the contrary, an important means of protection. The Crabs in question escape pursuit in consequence of this disguise, and it is to be observed that each species chooses the very material which makes it most unrecognizable to plant upon the exterior of its body; those species which live chiefly in regions where Cystosiras are indigenous deck themselves in Cystosiras, whilst those which inhabit the same places as Ulvæ carry Ulvæ on their backs.[308] This also serves as aggressive mimicry; for, as Mr. Woodward writes, "thus disguised like Indians stalking game, they can readily approach their more active prey."[309] Mr. Bateson observed this active mimicry at Plymouth, and describes how a Crab seizes a piece of weed, tears off a fragment, chews the end in its mouth, and then rubs it firmly on its head and legs until it is caught by the curved hairs and fixed. "The whole proceeding is most human and purposeful. Many substances, as Hydroids, Sponges, Polyzoa, and weeds of many kinds and colours, are thus used; but these various substances are nearly always symmetrically placed in corresponding parts of the body, and particularly long plume-like pieces are fixed on the head."[310] Dr. Willey records a similar observation which he made on the faces of rocks near Tjibodas (Java). "I found a quantity of small caterpillars living on the powdery Alga which makes greenish-white patches on the rocks. The caterpillars had so completely covered themselves with the Alga as to be only discernible by their movements on close inspection, and their disguise must effectually protect them from foes."[311] "Equally marvellous, too, is the case of many kinds of caterpillars which spin their cocoons on the bark of trees, and cover the structures wherein they are subsequently to undergo transformation into the chrysalis state with lichens and fragments of bark, that their temporary resting place may not be noticed by insectivorous birds."[312] When the caterpillar of the Indian butterfly, Limenitis procris, "comes out of the egg, it betakes itself at once to the very point of a tender leaf, and eats down steadily on both sides of the midrib, which stands out bare and dry. As the little thing advances it cuts up much more of the leaf than it eats, and these crumbs, with other refuse, are gradually accumulated, and loosely bound together with silk till they form a breastwork across the whole breadth of the leaf. Behind this rampart of refuse, of which its brown and ragged form seems to be a portion, the little architect lives, pushing the work back from day to day as it eats on."[313] Kirby and Spence pointed out many instances of the same active and intelligent mimicry. "Of this description is a little water-beetle (Elophorus aquaticus), which is always found covered with mud, and so when feeding at the bottom of a pool or pond can scarcely be distinguished by the predaceous aquatic insects from the soil on which it rests. Another very minute insect of the same order (Limnius æneus), that is found in rivulets under stones and the like, sometimes conceals its elytra with a thick coating of sand that becomes nearly as hard as stone." "A species of a minute coleopterous genus (Georyssus areniferus), which lives in wet spots where the Toad-rush (Juncus bufonius) grows, covers itself with sand; and another nearly related to it (Chætophorus cretiferus, K.), which frequents chalk, whitens itself all over with that substance. As this animal when clean is very black, were it not for this manœuvre it would be too conspicuous upon its white territory to have any chance of escape from the birds and its other assailants."[314]

Many examples of active mimicry are exhibited by our British moths, as may be learned by consulting the pages of Mr. Barrett's excellent work on the 'Lepidoptera of the British Islands.' Thus Eriogaster lanestris is an instance, for "even when sitting on a hawthorn spray it so accurately mimics a dead leaf twisted round the twig that it becomes almost impossible of recognition."[315] Cerura furcula sits in the daytime "on the trunk, or more usually on a branch, of one of its food-trees, its outstretched downy legs and grey markings giving it a most deceptive likeness to an entangled downy feather, or even a more close resemblance to a ripe sallow catkin from which the downy seeds are bursting."[316] Its larva feeds on sallow and willow. Petasia cassinea is said in the daytime "to sit upon old posts and railings, and is very hard to see, from its close resemblance to a bit of decayed wood, or to the greyish-brown lichens. Its extended and tufted feet, and rough scales at the edge of the fore wings, all help to complete the deception."[317] Cymatophora duplaris exhibits a purpose in active mimicry of the highest description, both as a caterpillar and a perfect moth. The larva during the day "conceals itself in a habitation formed of green leaves united by silken threads upon the tree. At night it comes forth to feed."[318] The moth sits in the daytime on the branches of trees. "When shaken out it falls straight to the ground, and lies among the dead leaves."[319] Arsilonche venosa, in colour and markings, like those of so many other fen-frequenting species, is accurately suited to its habit of hiding in the daytime among the dead leaves of reed, sedge, and marsh-grasses.[320] Agrotis ashworthii "sits in the daytime on limestone rocks, or hides among loose stones. In appearance it closely resembles the blue limestone, and it has the sagacity to hide itself in chinks and crevices, where this resemblance greatly assists in its concealment."[321] All these examples scarcely bear out an automatic or semi-automatic action; we seem to see among these lowly organised insects—referring, of course, to sense organs—a capacity and endeavour to use their environmental resemblances to the best advantage. There may be much heredity in such an aptitude, but the intelligent concealment would not be questioned if practised by the higher animals.

The instances of active mimicry just given almost appertain to decorative art, and in fact represent the impostor who with borrowed plumes flaunts in the open. We now resume the series of more modest simulation, in which advantage is taken of similarly coloured objects by which concealment may be effected. These may nearly be said to reflect the methods of the impostors who attach themselves to majorities, winning causes, and crowds, where they are submerged in resemblances, and, undetected, reap the corresponding advantage. The Australian genus of Seahorses (Phyllopteryx sp.) "closely resemble the colour of seaweeds to which they attach themselves, while the filamentous appendages of their spines appear as if they were actually a part of the vegetable growth."[322] The Dragonfly larva "trusts chiefly to its sombre colouration and its motionless attitude. The larva clinging to a stem in the shady recesses of water-weeds is not easily distinguished, and the absence of movement removes the chief risk of discovery."[323] Many caterpillars resort to the bark of trees, with which their colour and often notched, knotted, or spotted bodies closely assimilate. That this is a form of active mimicry may be gleaned from the remarks of a British entomologist:—"A number of these mimics of the insect world never venture to feed by day, but take in their quantum of provision during the dark hours, and practise their deceptions during the day."[324] Active mimicry may also explain resemblances which Weismann is very emphatic in denying as due to "external influences." "If a caterpillar, which hides itself by day in the crevices of the bark, possesses the same colour as the latter, whilst other caterpillars which rest on leaves are of a green colour, these facts cannot be explained as the result of the direct influence of the bark and leaves. And it would be even less possible to explain upon the same principle all the details of marking and colour by which these animals gain still further protection. If the upper side of the upper wings of certain moths is grey like the stone on which they rest by day, while in butterflies the under side of both wings which are exposed during rest exhibits analogous protective colours, these facts cannot be due to the direct influence of the surroundings which are resembled; but, if they have arisen in any natural manner, they must have been indirectly produced by the surroundings."[325] These last remarks appear to be obscure. Surely, to make the proposition clear, some explanation should have been given as to what is meant to be differentiated between "cannot be due to the direct influence of the surroundings," and "must have been indirectly produced by the surroundings." And therefore, perhaps Prof. Weismann is scarcely justified in observing, "one may reasonably complain when compelled to repeat again and again these elements of knowledge and of thought upon the causes of transformation."[326] A recent writer would apparently regard the Phasmidæ as examples of active mimicry. He is reported as saying:—"Amongst true instincts he would class such acts of protective mimicry as those performed by the Phasmidæ, although their alleged practice of shamming death might possibly be constitutional lethargy, which had misled observers."[327] We have already recorded Mr. Belt's observation in Nicaragua as to the behaviour of a leaf-like Locust when surrounded by a host of predaceous Ants. A somewhat similar fact has been narrated by "Eha":—"I was sitting high up in a tree, rifle in hand, waiting for a Tiger, when my attention was caught by one of these Crickets (exactly resembling a small patch of grey lichen) scurrying round the trunk of a neighbouring tree, with a Lizard in full pursuit. Just as the Lizard came up with it the Cricket, falling in with a slight depression in the bark, stopped dead, and flattened itself out, and the Lizard was utterly confounded. There it stood, looking ludicrously puzzled at the mysterious disappearance of its prey, which was just under its nose."[328] The Horned Frog (Ceratobatrachus guentheri) of the Solomon Islands is described by Mr. Guppy to so closely imitate its surroundings, both in colour and pattern, that on one occasion he captured a specimen by accidentally placing his hand upon it when clasping a tree.[329] This species is so variable in colouration and in the integuments, that Mr. Boulenger has remarked, "Out of the twenty specimens before me no two are perfectly alike."[330] This is probably a case of what is here considered active mimicry.

Birds exhibit many illustrations of active mimicry. A recent writer in 'The Zoologist' called attention to some peculiar "attitudes of a Little Bittern observed in captivity." The real meaning of the attitudes of this bird (Botaurus minutus) seem only to have been understood by the then editor, Mr. Harting, who thus comments on the same:—"The inference to be drawn from these remarks is that the curious attitudes adopted by this bird, on finding itself observed, are assumed in the exercise of what may be termed the instinct of self-preservation, and in a state of nature must tend materially to favour its concealment. Whether it be standing in or near a reed-bed, erect, with neck preternaturally elongated and beak pointed upwards, or crouching against a riverside tree-stump, the attitude is calculated to deceive the eyes of all but the keenest observers, especially since the colour of the bird's plumage harmonizes in a remarkable degree with that of the natural surroundings."[331] Mr. Hudson has made a similar remark concerning the Common Bittern (Botaurus stellaris). "His buff and yellow and chestnut colour, mottled and barred and pencilled with black and brown, gives him a strange tigrine or cat-like appearance; it is a colouring well suited to his surroundings, where yellow and brown dead vegetation is mixed with the green, and the stems and loose leaves of the reeds throw numberless spots and bars of shade beneath. Secure in its imitative colouring, the Bittern remains motionless in its place until almost trodden upon."[332] A very similar proceeding, as far as intention is exhibited, though appertaining more to what is understood by "aggressive mimicry," is to be found in the account of the habits of the Cassowary (Casuarius bennetti), given by Mr. Wilfred Powell as observed in the island of New Britain:—"I saw a Morroop (Cassowary) come down to the water's edge, and stand for some minutes, apparently watching the water carefully; it then stepped into the river, where the water was about three feet deep, and, partially squatting down, spread its wings out, submerging them, the feathers being spread and ruffled. The bird remained perfectly motionless; I also noticed that the eyes were closed, as if asleep. It remained in this position for fully a quarter of an hour, when, suddenly closing its wings and straightening its feathers, it stepped out on the bank, where, shaking itself several times, a quantity of small fishes fell from under the wings and from amidst the feathers, which were immediately picked up and swallowed. The fishes had evidently mistaken the feathers for a description of weed that grows in the water along the banks of the rivers in this island, and very much resembles the feathers of the Cassowary, and in which the smaller fish hide to avoid the larger ones that prey on them."[333] The Ruffed or Birch Partridge in Canada has been described by Dr. Leith Adams as flying to a tree to escape danger, where "their statue-like posture, with neck outstretched, and their motionless position on the moss-clad spruce-bough, render it extremely difficult to recognize them." So close is this active mimicry carried out that it is sometimes only by the barking of Dogs that the sportsman is aware of the close proximity of the birds. In the words of Dr. Adams, describing an actual experience, "In vain we looked, for no Partridge was to be seen; still the Dog barked, and began to bite and tear off the bark, when at length three birds were discovered standing motionless on the moss-covered boughs, and within a few yards of us."[334] Even more forcibly Mr. Anthony, of San Diego, California, describes the active mimicry of the "Long-eared Owls," who can assume a "rigid, stick-like position" to the surrounding shrubs and branches. "To escape notice—so great is their faith in the protection afforded them by this resemblance, when several are together, as is often the case in winter—one or more may be shot without the rest showing so much as by the movement of a feather that they are disturbed." On one occasion a friend with whom he was hunting came upon five of these Owls sitting in a row on a limb of a giant cottonwood. "Beginning at one end of the line, he shot them all, one after another, his last shot starting a sixth, which he had not seen, from a perch in the same tree."

When Mr. Anthony arrived upon the scene they began looking for the escaped Owl, but failed to discover it. "As we were leaving, however, my eyes chanced to fall upon what at first appeared to be an abnormal growth on the trunk of a small sapling near us, but which, upon a second glance, proved to be a little Screech-Owl. With its back against the trunk of a tree it was drawn up to its fullest height, all its feathers drawn tight against its body, its ear-tufts erect. It looked to be twice its normal length, and so closely did it resemble the grey bark and branches that, unprotected as it was by leaves or twigs in the strong glare of a bright winter's day, its discovery was purely accidental. Our tracks in the snow proved that we had several times passed within ten feet of the bird, and it was quite evident that it was aware of our presence; for, while it made not the slightest movement, it watched us constantly through its halfclosed lids, trusting no doubt to escape detection, but ready to fly if the occasion required."[335]

Geese and Ducks seem to mimic snakes. In the opinion of Mr. Louis Robinson:—"It seems very probable that the hiss of the Goose, when it desires to show hostility, is founded upon the hiss of the serpent. Many Ducks also, when nesting, will thrust out their necks and hiss when an intruder approaches, and a Muscovy drake is almost as ready to adopt this method of intimidation as a gander. It is found that nearly all long-necked birds which nest among reeds and bushes show a similar habit. One can easily understand that among thick grass or reeds, where only the head and neck of a nesting Duck are visible, the forward dart and hiss might often be sufficient to deter a cautious enemy from making an attack."[336]

I have related my own experience in the Transvaal with Francolinus levaillantii, a single member of which from a covey I had disturbed squatted in a small hole in the path about eighty yards in front of me, and, depressing its back level with the earth, exhibited a good instance of the protection obtained by assimilative colouration.[337] A young Merganser deceived the Duke of Argyll and a party of his visitors at Inverary by simply remaining perfectly still on ground on which it was inconspicuous by reason of the protective resemblance or mimicry of its colour.[338] Mr. R. Kearton states:—"I have on more than one occasion seen a baby Peewit wandering about with half of its prison-house still attached to its downy rump, and if a Hawk or other bird of prey should happen to appear overhead they instinctively clap flat upon the ground, and remain motionless as stones until the danger has passed."[339] The Dabchick, on quitting the nest, according to Mr. Hudson, "invariably draws a coverlet of wet weeds over the eggs; the nest in appearance is then nothing but a bunch of dead vegetable rubbish floating in the water."[340] Young Emus are very different in colour from the old birds, and bear a delicate design of a pretty dark grey with numerous stripes on their back and sides. Mr. Semon relates:—"Young Emus are often pursued by Eagles and Hawks so frequent in Australia. When (so my blacks told me) the young Emus see a bird of prey soaring above them they quickly lie down flat upon the ground. A body as big as theirs would surely be much more conspicuous, set off as it is by grass, if it were evenly though ever so modesty coloured, than if its colouring be varied by stripes and spots. I myself have had occasion to notice how difficult it is to discover an Emu in the grass if it nestles to the ground."[341] Gilbert White remarks on the Stone Curlew (Œdicnemus crepitans):—"The young run immediately from the egg like Partridges, &c, and are withdrawn to some flinty field by the dam, where they skulk among the stones, which are their best security, for their feathers are so exactly of the colour of our grey-spotted flints, that the most exact observer, unless he catches the eye of the young bird, may be eluded."[342] The same observer records an illustration of active mimicry in a Willow-Wren:—"This bird a friend and myself had observed as she sat in her nest, but were particularly careful not to disturb her, though we saw she eyed us with some degree of jealousy. Some days after, as we passed that way, we were desirous of remarking how this brood went on; but no nest could be found, till I happened to take up a large bundle of long green moss, as it were carelessly thrown over the nest, in order to dodge the eye of any impertinent intruder."[343]

Active mimicry, rather than natural selection per se, appears very largely to account for the assimilative colouration of birds' eggs to their nests or environment. Without recapitulating all the evidence which can be readily obtained from so many sources—either by observation, or reference to much illustrated literature—we may safely conclude, with Mr. Wallace, that on the whole, "while white eggs are conspicuous, and therefore especially liable to attack by egg-eating animals, they are concealed from observation in many and various ways."[344] This is a very important consideration before we proceed farther. We find a great number of white or prominent eggs, apparently unaffected by "natural selection," but preserved by intelligent concealment, which is only a form or phase of what we have noted before, and to what will be referred to again on this very matter of birds' eggs, as active mimicry. If the process of natural selection was to be applied, according to a very frequent method, as universal, then birds arising from these white and prominent eggs would seem in course of time to be doomed to destruction. But we find nothing of the kind. Natural selection is here replaced by the evolution of intelligence or active mimicry. True, it may be argued that birds laying white eggs would become extinct without they had gradually acquired the intelligent or automatic powers of concealment through a process of natural selection. But this is only begging the question. The colour of the egg has not altered under this severe stress, and we can see that many eggs are completely either adapted to their environment, or are so marked and coloured that the birds by choosing a proper environment, or, again, exercising active mimicry, can leave such in practical exposure. "Primarily the eggs of birds must have been white, from the inherent colour of the salts of lime and magnesia of the shell."[345] "As a rule, Sandwich Terns' eggs harmonize closely with their surroundings, and even the experienced field naturalist has to exercise a great deal of care to avoid treading upon a clutch when visiting a breeding station. A friend of mine told me a few years back that he had once visited a colony of these birds on an island where the natural breeding accommodation was so limited that many of them had conveyed patches of pebbles on to the grass, and laid their eggs thereon."[346] Take, for instance, our Nightjar or Goat-sucker. As Mr. Watson has remarked, "this night-flying bird, half-Owl, half-Swallow, rests during the day on bare bits of limestone on the fells. Its mottled plumage exactly corresponds with the grey of the stones, and its eggs, in colour like its plumage, are laid upon the bare ground without the slightest vestige of a nest, and again entirely resemble the stone."[347] Now take another good example from Mr. Wallace. The common Black Coot (Fulica atra) "only breeds in certain localities where a large water-weed (Phragmites arundinacea) abounds. The eggs of the Coot are stained and spotted with black on a yellowish-grey ground, and the dead leaves of the reed are of the same colour, and are stained black by small parasitic fungi of the Uredo family; and these leaves form the bed on which the eggs are laid. The eggs and the leaves agree so closely in colour and markings that it is a difficult thing to distinguish the eggs at any distance. It is to be noted that the Coot never covers up its eggs as its ally, the Moor-hen, usually does."[348] Mr. Wallace considers that these eggs "are coloured in a specially protective manner," but it is equally open to argument, that as white eggs are concealed, and the mottled-grey egg of the Nightjar laid on the similarly coloured ground, so the concealing, or active mimicking, powers of the Coot suggest its placing its eggs among the leaves that so successfully hides them.

That birds may use a reasoning or cunning attribute in the deposition of their eggs where the colouration may prove of an assimilative character to the surrounding environment may be argued from the evidence which exists of their pursuing an equivalent mental process in the placing of their nests. Thus recently a writer has described "some curious experiences in birds' nesting." He found a Blackbird's nest "situated in a depression in the ground, in just such a position as a Sky Lark's might occupy." A keeper who accompanied him had found several other Blackbirds' nests in similar positions. Within a few hundred yards two Thrushes' nests were also found on the ground, "the edge of the nests being level with the surface." On enquiry it was stated "that the proprietor, having found that this wood was a nesting stronghold of these species, had made systematic raids on their nests in consequence of the havoc made by the birds on his fruit. I think this fact suggests why these birds had departed from their usual habit in their choice of nesting sites. Profiting from experience, they had selected safer positions." The same writer records facts to prove that the Common Sandpiper "profits by experience, and occasionally varies its choice of nesting sites." In 1886 these birds had their nests twice swept away from the river-banks by heavy floods. In the following year nests were found fully a hundred yards from the river. "From May, 1886 (the date of these floods), until 1889, the Sandpipers continued to nest at some distance from the river."[349] The Sumoan Tooth-billed Pigeon (Didunculus strigirostris), which formerly bred on or near the ground, and was so greatly reduced in numbers by Cats as to be threatened with extermination, eventually took to nesting and roosting in trees, and has since been gradually on the increase."[350] We have not yet reached the explanation of the colours of eggs; we have only by observation seen—under "natural selection," if you will, or active mimicry—how avian subterfuge has in so many cases combated the pertinacious search of the persistent enemies to bird existence.

Sometimes this mimicry appears only as a survival, and when its character is no longer protective. "The bird which in the arctics long ago lined its nest with green moss or grey lichens may now floor it with flax in Dakota, or pad it with cotton in Texas; and yet in either deposit a solid green or mottled greyish egg in keeping with the colours of 'the old house at home.'"[351] Thus the eggs of the Wild Duck are placed among the green reeds, while those of the Lapwing are with equal confidence consigned to the ploughed field or upland. The Red Grouse can safely leave its speckled eggs among the heather; the Lesser Tern has little fear that its spotted egg will be noticed on the shingle, or the Ringed Plover that its egg will be readily distinguished from the sand on which it is laid. Take Mr. Seebohm's 'History of British Birds,' with its beautiful illustrations of eggs, often so decisive in colour and markings, and then find the eggs in their natural surroundings, and one will then experience how "the whole creation groaneth," or rather the intense beauties and harmonies that have arisen in Nature because she "is red in tooth and claw."

Mammals contribute the same evidence, and the narratives of sportsmen and travellers afford many instances. According to Mr. Buxton, the Sardinian Mouflon (Ovis musimon) was one of the most difficult animals to approach with which he was acquainted. He observes, that "when they are alarmed, or 'at gaze,' they have a habit, or at least the rams have, of placing themselves in the middle of a bush of Macquia, or in the shadow which it casts. The ewes, who are naturally less conspicuous, do this in a less degree."[352] The same authority describes a similar habit in the Barbary Sheep (Ovis tragelaphus), known by the name of "Aroui": "They are constantly within sight and hearing of the Arabs and their Goats, and, having no means of escaping from their neighbourhood, have developed the art of hiding themselves to an extraordinary degree, and their confidence in their own invisibility is unlimited. A practical illustration of this occurred to me one evening when I had sat in one place for twenty minutes carefully spying the surrounding country. My coign of vantage was a knoll which commanded a small shallow hollow, in which there was not a vestige of cover, except the few thin thuja bushes which looked as if they could not hide a Rat. It was not till I rose to shift my position that a female Aroui and two yearlings started from these bushes. They had been lying within sixty yards of me, and must have been fully conscious of my presence."[353] Le Vaillant writes: "If the Giraffe stands still, and you view it in front, the effect is very different. As the fore part of its body is much larger than the hind part, it completely conceals the latter; so that the animal resembles the standing trunk of a dead tree."[354] Mr. Baines, the African traveller, related to Frank Buckland that "the Giraffe seems to know that if he keeps perfectly quiet he will be mistaken for a tree; if he moves, his presence will become apparent to his enemy—man."[355] Baines himself has recorded that a Giraffe he watched passing through the bush looked "for all the world, as he stopped to gaze, like the white stump of a dead tree, which anyone might have passed by without suspecting it of the power of motion."[356] Sir Samuel Baker bears the same witness: "It may be readily imagined that, owing to the great height of this animal, it can be distinguished from a distance, and does not require an elaborate search; nevertheless, it is exceedingly deceptive in appearance when found among its native forests. The red-barked mimosa, which is its favourite food, seldom grows higher than fourteen or fifteen feet. Many woods are almost entirely composed of these trees, upon the flat heads of which the Giraffe can feed when looking downwards. I have frequently been mistaken when remarking some particular dead tree-stem at a distance, that appeared like a decayed relic of the forest, until, upon nearer approach, I have been struck by the peculiar inclination of the trunk: suddenly it has started into movement and disappeared."[357] Gordon Cumming narrates a similar experience:—"In the case of the Giraffe which is invariably met with among venerable forests, where innumerable blasted and weather-beaten trunks and stems occur, I have repeatedly been in doubt as to the presence of a troop, until I had recourse to my spyglass, and on referring to my savage attendants I have known even their optics to fail, at one time mistaking these dilapidated trunks for camelopards, and again confounding real camelopards with these aged veterans of the forest."[358] Mr. Vaughan Kirby says: "They stand perfectly still, not even swishing their tails like wildebeeste, and thus bringing about instant recognition; their mottled or dark colour, great height, and comparatively narrow bodies give them a striking resemblance to the many old vari-coloured relics of the forest, blasted by lightning or by bush-fires."[359] Col. Pollok attributes the same habits to the Indian Elephant (Elephas indicus):—"If nature has not given intellect to these animals, it has given them an instinct next thing to it. One has only to hunt them in their wilds to learn how wonderfully Providence has taught them to choose the most favourable ground, whether for feeding or encamping, and to resort to jungles where their ponderous bodies so resemble rocks or the dark foliage that it is most difficult for the sportsman to distinguish them from surrounding objects."[360] Gordon Cumming relates a similar experience in South Africa with regard to Elephas africanus:—"The ashy colour of his hide so corresponds with the general appearance of the grey thorny jungles which he frequents throughout the day, that a person unaccustomed to hunting Elephants, standing on a commanding situation, might look down upon a herd and fail to detect their presence."[361] An even stronger case, or more pronounced opinion, as to active mimicry is given by the American naturalist E.S. Thompson, and a Fox is the animal referred to:—"A fire had swept the middle of the pasture, leaving a broad belt of black; over this he skurried till he came to the unburnt yellow grass again, when he squatted down and was lost to view. He had been watching us all the time, and would not have moved had we kept to the road. The wonderful part of this is, not that he resembled the round stones and dry grass, but that he knew he did, and was ready to profit by it."[362] According to Livingstone's observations on a small Antelope named "Tianyáne":—"When the young one is too tender to run about without the dam, she puts one foot on the prominence about the seventh cervical vertebra, or withers; the instinct of the young enables it to understand that it is now required to kneel down, and to remain quite still till it hears the bleating of its dam, If you see an otherwise gregarious she-Antelope separated from the herd, and going along anywhere, you may be sure she has laid her little one to sleep in some cosy spot. The colour of the hair in the young is better adapted for assimilating it with the ground than that of the older animals, which do not need to be screened from the observation of birds of prey."[363] "Rabbits open their nesting burrows and suckle their young by night, closing them lightly with earth again when they leave them. I had a nest under close observation last spring, and was much interested to find that its owner scattered some old hay from a Sheep fodderingstation close by, over the mould with which she filled the entrance to the burrow every time she left it, a procedure which materially lessened its chances of being discovered."[364] We can find another example in the East. In the South Mahratta country, according to Sir W. Elliot, it is a common belief of the peasants that in the open plains, where there is no cover or concealment, the Indian Wolves (Canis pallipes) scrape a hole in the earth, in which one of the pack lies down and remains hidden while the others drive the herd of Antelopes over him.[365] The usual colour of these animals is a greyish fulvous, generally with a brownish tinge, so that active or aggressive mimicry is thus obtained. A similar explanation may be applied to the fact described by Capt. Scannon respecting the Californian Sea-lion (Otaria gillespii). This animal, when in pursuit of a Gull, "dives deeply under water, and swims some distance from where it disappeared, then, rising cautiously, it exposes the tip of its nose above the surface, at the same time giving it a rotary motion like that of a water-bug at play. The unwary bird on the wing, seeing the object near by, alights to catch it, while the Sea-lion at the same moment settles beneath the waves, and at one bound, with extended jaws, seizes its screaming prey, and instantly devours it.[366] Waterton has given a very similar suggestion. Beneath some agitated birds, and in the long grass, he saw what was apparently "a pale green Grasshopper," fluttering as though entangled in it. "Nothing more remained to be done but to wait in patience till it had settled, in order that you might run no risk of breaking its legs in attempting to lay hold of it while it was fluttering—it still kept fluttering, and, having quietly approached it, intending to make sure of it—behold, the head of a large Rattlesnake appeared in the grass close by.... What had been taken for a Grasshopper was, in fact, the elevated rattle of the snake."[367] Aflalo has remarked:—"The snake's power of fascinating birds is another moot point, on which Dr. Stradling has offered about the best suggestion, fully endorsed in Miss Hopley's charming book. His opinion is that the birds mistake the quivering tongue for a worm or insect, and that organ, considered by the ignorant to be endowed with 'stinging powers,' may consequently act as a bait to lure the incautious food within reach of the fatal jaws."[368] The Tree-Frog (Hyla) is of a light green colour when seated upon a light green leaf, but becomes dark brown when transferred to dark surroundings. "Hence this animal adapts itself to the colour of its environment, and thus gains protection from its enemies."[369]

 

(To be continued.)

 

 

BIOLOGICAL SUGGESTIONS.
MIMICRY.

By W.L. Distant.

(Concluded from vol. iii. p. 553.)

Active mimicry naturally predicates intelligence, and is not equivalent to what is generally described as instinct,[370] so universally applied to any other animal than man. Prof. Lloyd Morgan remarks on the many who believe that instinct is neither more nor less than inherited habit, but concludes that, "while still believing that there is some connection between habit and instinct, admit that the connection is indirect and permissive rather than direct and transmissive."[371] Every attempt is made to minimise this faculty. In birds, Mr. Orr has warned us not to overrate the intelligence implied by nest-building "of an animal which has not sufficient intelligence to loosen a slip-knot tied around its leg."[372] But man himself has very slowly and laboriously acquired—and has not yet altogether the desire to possess—the intelligence to loosen the artificial slip-knots that bind him to many errors and much superstition. If, however, some would minimise animal intelligence, there are others who maintain the purposive acts of plants. Thus Mr. Grant Allen, in describing the wonderful life-history of the common gorse, and allowing that "the intelligence is here no doubt unconscious and inherited," still remarks: "Gorse, in short, may fairly be called a clever and successful plant, just as the Bee may be called a clever and successful insect, because it works out its own way through life with such conspicuous wisdom."[373] The same spirit runs throughout Dr. J.E. Taylor's 'Sagacity and Morality of Plants.'

Animal intelligence has been opposed by two great factors—the philosophy of Descartes[374] and theological dogma. The first is clearly intelligible and ably stated; the second is more of an implication, but both are based on the belief of man's special immortality; and, although divines are found[375] who are willing to extend the promise of a future life to the whole animal kingdom, and have discovered texts to advocate that view, the Hebrew Scriptures can scarcely be said to strongly support it. Even the poor untutored Todas of India, who are alone valued as an ethnological study, have at least a kinder and more sympathetic heart for their cattle. The sum of their belief is, that they were born—they and their cattle somehow rose out of the earth. When they die they go to Amnôr (the next world), which is a world exactly like this, whither their Buffaloes join them, to supply milk as in this state.[376] Sir Herbert Maxwell, in discussing our obligations to wild animals, states, as a "remarkable and perplexing fact, that neither the chosen people nor Christians are bound by their religion to pay the slightest regard to the feelings of animals. . . . There is not a word about mercy towards dumb animals in the Sermon on the Mount; not a word in all the writings of the Fathers (so far as known to me); not a word, apparently, from all the teachers of Christianity until we reach the dawn of rationalism in the eighteenth century, when an English country clergyman—the Rev. Mr. Grainger—scandalized his congregation and jeopardized his reputation for orthodoxy by preaching the duty of humane treatment of beasts and birds."[377] But if evolution is not a farce, and man has been derived from more lowly ancestors, then the possession of a soul—using the term in the ordinary signification as taught to ordinary people—must imply either its existence in the whole animal world, or its gradual evolution[378] with the specialization of type, both of which premises are outside scientific reasoning, and therefore quite beyond the cognizance of plain folk. To deny conscious intelligence is a corollary to denying immortality to animals, and it is often the desire to monopolise the last that so frequently ensures the denial of the first.[379] The writer of 'Ecclesiastes' had nursed the thought—"Who knoweth the spirit of man whether it goeth upward, and the spirit of the beast whether it goeth downward to the earth."

That animal intelligence is sufficient to prove much mimicry of an active and not of a merely passive character, is abundantly advocated by facts. That an insect or bird should seek and obtain concealment by its own volition, and by a sense of adaptation in bringing into juxtaposition its own peculiarly-coloured body with some material object with which it closely assimilates, is an exemplification of intellect, though inferior to that shown in the general psychology of Bees, Wasps, and Ants. In Birds it would rank lower than the acquired and more complicated knowledge of the African Honey-bird, which is able to associate the appearance of Man with that of a honey-seeking creature, and to lure and lead him to the nest of the Bee, in order that his assistance and strength may wreck the nest and leave the bird what it requires in the débris that remains after the auxiliary's wants are satisfied. "A Green Frog will with predilection rest on green leaves. The advantages of concealment are obvious, and in this case he 'adapts himself' to the surroundings by making for green localities; if he did not he would be eaten up sooner than his more circumspect comrades. But this making for, and sitting in, the green has has not necessarily made him of that colour."[380] As Dr. Reid forcibly enquires, "By what term shall we designate the action of the Spider when he builds his web? Does the animal not know for what purpose he constructs it? Was there ever a web-building in which there were not circumstances novel alike to the experience of the individual and to that of the species? Or, when he runs along a thread to capture his prey, or cuts loose a dangerous captive, does he not consciously adapt means to ends, just as much as a man who runs to secure a snared bird, or who builds a 'golden bridge' for a flying enemy?"[381] What angler does not know the greater difficulty in filling a basket from a stream much fished, than from one little visited by anglers, and how the greater skill required is not an incident of fewer fish, but of the greater caution acquired by the same? The Marquess of Granby truly observes: "Of course, at the date when Canon Kingsley went a-fishing, Trout were easy to catch compared with what they are now, at any rate in the best known English rivers." .... "Trout, being very much fished over," in many cases from over-weed-cutting, &c, "are highly educated and more difficult to kill than ever they were before."[382] A recent writer has illustrated this fact. Mr. Basil Field, describing his experience in fly-fishing, states:— "If a fly be cast in one of Mr. Andrew's stock-ponds at Guildford, there is a rush and fight for it among all the Trout within whose range of vision it falls. If it be cast again a few minutes after a Trout has been caught and returned to the water, two or three fish only will compete for it. Repeat the process, and perhaps one may come, slowly, shyly, and in a half-hearted manner. But when several have been taken and returned—although the pond is large and crowded with fish—cast the fly where you will, the Trout are shy, suspicious, and hard to catch."[383] Prof. Mcintosh, with reference to the absence of the cortex of the brain in fishes, observes, "Who has proved that the function of memory depends on the brain-cortex of the human subject? I have seen many a curious case in the pathological room, the history of which would not have have led us to this conclusion."[384] According to Livingstone, the Hippopotamuses in the rivers of Londa, where they are much in danger of being shot, gain wit by experience; for while those in the Zambesi put up their heads openly to blow, those referred to keep their noses among water-plants, and breathe so quietly that one would not dream of their existence in the river, except by footprints on the banks."[385] In the Leeba, Crocodiles possess more of the fear of man than in the Leeambye. The Balonda have taught them by their poisoned arrows to keep out of sight. "We did not see one basking in the sun."[386] Nansen remarks:—"Curiously enough, one can, as a rule, get nearer to the Seal with the larger vessel than with the boats. They have learned to fear the latter, and often take to the water quite out of range, while one can sometimes bring the ship right up to the floe on which they lie before they decamp."[387] On the solitary St. Paul's Rocks, situated between the equatorial coasts of Africa and South America, Sir C. Wyville Thomson, at the visit of the 'Challenger,' writes: "In the morning both the Booby and the Noddy were quite tame, but towards afternoon even these few hours' contact with humanity had rendered them more wary, and it was now no longer possible to knock them down with sticks or stones."[388] Semon had a similar experience in Queensland. "On removing my camp to new hunting-grounds, I used to have no difficulty during the first days in stealing up to the water-birds so as to get within shooting range. In an incredibly short time, however, they became shy, and then they were by no means inferior to their European relations in prudence and caution."[389] Sir Joseph Banks, when in New South Wales with Capt. Cook, found most of the birds "extremely shy, so that it was with difficulty that we shot any of them."[390] The few travellers who have had the great good fortune to visit a little known and unfrequented island have told us what small fear other animals have for their colleague Man, till they have experienced his destructive propensities, and then how quickly reserve, shyness, caution, and fear rapidly become dominant factors in a hitherto peaceful existence.

Of course there are exceptions to this rule, especially among birds. According to Mr. Macpherson, the tameness of the Ortolan Bunting as observed by him in Spain "is almost ludicrous. So little do they apprehend injury, that they will allow visitors to lie on the grass while they forage round for earthworms."[391] The writer's own experience in the Transvaal is precisely similar with respect to the Pied Babbling-Thrush (Crateropus bicolor). If I lay down at the edge of bush and kept quiet, these birds would not only come close to me, but remain there. Again, Curlews and Golden Pheasants are wild in whatever part of the world they are found, even where the report of a gun has never been heard.[392] According to Dr. Leith Adams, in Canada "the Purple Swallow has now such a predilection for man's society, on account of the preponderance of insect life which invariably surrounds him wherever he goes, that he has only to construct a small cot with several chambers, and place it on a pole at the door of any solitary shanty in the wild wilderness, when year after year, with the certainty of the seasons, it will be tenanted by these birds in preference to any other situation."[393] The sound of firearms does not at first universally create terror in birds. D'Albertis relates that, when "fishing with dynamite," "an Haliastur sphenurus, with its female, and a young one already able to fly, were perched on the branch of a tree, interested at this novel method of fishing, and not in the least alarmed by the detonation. When I had finished, the male and female picked up the little fishes which I left, and took them to their young one."[394] Eimer, when staying in the Dutch island of Rottum, in West Friesland, found the Water-Rail (Rallus aquaticus), "which is usually so shy, ran about close to me in the ditches so fearlessly that I could almost have caught it with my hands. This island is let by the Dutch Government to an egg-bailiff, whose duty consists in collecting birds' eggs, and therefore no bird is allowed to be hunted there; it is especially forbidden to shoot at them."[395]

On the other hand, wild animals have chosen to seek the protection of man when pursued by their enemies. The African traveller Anderson once had a Blesbok take refuge at his camp-fire when pursued by Wild Dogs. He also states:—"I have known small birds fly to my waggon and into it, on several occasions, when pursued by Hawks."[396] Andrew Steedman once witnessed a herd of Gnus pursued by a Lion. "The affrighted animals seemed to seek the vicinity of our waggon as a protection from their formidable enemy."[397] A lady, describing a great grass and forest fire which took place in South Africa in February, 1869, writes: "The poor Hares and Wild Bucks came to the houses for protection from the flames."[398] Another narrator elsewhere states: "Wild Bucks from the surrounding bush came and crouched about, terror-stricken, and one, half scorched to death, took refuge on the stoop of the building."[399] Col. Ward, describing the "hawking" of Jackdaws in the Peshawur Valley, says that a Jackdaw, when closely pressed, "would make straight for the nearest human beings he saw, fly round the men, under the horses' girths, into a dog-cart or buggy, if there was one, and do his utmost to dodge his pursuer, often causing a regular stampede among the horses, for they could not at all understand the two birds flying about among them in this way."[400] According to the Comte de Canteleu, Stags nearly always make for the abodes of men when they are sinking.[401]

On the other hand, "the Cattle-Heron (Ardea russata), in Egypt, when fleeing before the sportsman, shelters itself under the Oxen and Buffaloes, because it knows that it is there protected from his gun."[402] Bonitos and Albicores may be often observed to congregate about the stern of a ship to escape the attacks of Sword-fish.[403]

Audubon relates that in the Missouri region of North America, while a number of Indian chiefs were conferring with, and angrily talking to, Mr. Chardon, "he sitting with his arms on a table between them, a Dove, being pursued by a Hawk, flew in through the open door, and sat panting and worn out on Mr. Chardon's arm for more than a minute, when it flew off."[404] Baldwin saw a broken-winged Golden-Goose chased by three Crocodiles. Eventually the bird took to the bank, and the poor thing "allowed me to catch him on land sooner than face his enemies in the water again."[405]

To fully understand mimicry we must appreciate general animal intelligence, and then we shall probably comprehend how much activity has been displayed by animals seeking protection by adaptive and assimilative efforts. This in no way contradicts, but supports, the doctrine of Natural Selection. The animal survives that can best hide from its enemies,[406] and this implies that the variations that tend to adaptive and assimilative efforts not only succeed in the battle of life, but by the selective process become dominant, and more and more accentuated with a greater need. Mimicry in the lower animals finds its equivalent in what is described as "tact" among men. Few possess it strongly, many slightly, and more not at all; while others in the struggle for existence depend on different means, and use more varied stratagems. Tact is often a silence which mimics the modest reticence of a learned man and thus conceals the ignorant. It appears as the bluster of the psychological moment when the coward receives an immunity from his protective resemblance to the brave; the rogue often succeeds by mimicking the devout; the sneak assumes the garb of frankness; the lie only triumphs when it simulates the truth.[407] On the other hand, we must not overvalue the efficacy of all these attempted concealments. They are not all successful,—nothing is, absolutely,—but are still means to an end. We are too apt to consider a disguise perfect because we have only accidentally discovered it, while at the same time our existence does not depend upon the result of the search. An amateur or an arm-chair naturalist is speechless with wonder at the least exhibition of wood-craft, a common attribute of many agricultural labourers and gypsies. Jefferies has accurately diagnosed the sense perceptions of a young gamekeeper:—"He will decide at once, as if by a kind of instinct, where any particular bird or animal will be found at that hour." And in a similar manner, but in a greater degree, will be formed the destructive experience of the bird or mammal whose life depends upon the discovery of its prey. Mimicry makes the successful search more difficult, the accidental escape more frequent, and actual extermination by such means alone, impossible. The enemy in his close pursuit finds other prey to satisfy his hunger, like the gold prospector who in his quest may come across non-auriferous minerals which tend to assuage his financial longings; and so an average of destruction is reached, and none alone are compelled to be "confessors" to nature's inexorable rule.

It is probable that highly protected or mimicking species are only destroyed by their most acutely sense-organized enemies, and have a general immunity from the attacks of the ordinary animal pirates. We have no more reason to predicate a dead level in the intelligence of a single species or genus of animals than we have to believe that the same character exists in Homo sapiens himself. For in nature, pace Ecclesiastes, the race is to the swift, and the battle is to the strong, though the exceptions of "time and chance" may prove the rule. Stroll along a trout stream when anglers are at work, and notice how empty baskets reward the majority, or those who perceive not. Now observe the skilled killer of Trout, how he will detect a hidden fish under the opposite bank, and soon possess the same.[408] Knowledge of habits combined with power of eye and hand are successful, and command the intense respect of the ordinary floggers of the stream. We may possess the most accurate knowledge of whist, and play according to the strictest rules, but one of the quartette is a Napoleon in the game, he judges and acts with an instinctive finesse, and the odd trick is won. Or take the boys in a large stable who are trained to ride racehorses at exercise: how few become jockeys; to possess "hands," judgment, nerve, and a knowledge of pace is only an occasional gift of the gods. And so in nature at large; all are not masters of the game, and the mimicking species have a general immunity from attack, save from those incontestable creatures who amongst all animal life, including our own, levy their own rates, successfully collect their own tithe, and command the attention, if not always the love, of their fellows. Animal disguise and mimicry serve an ever purpose, if they do not constitute a constant end; they are often partial and exceptional, and not in result universal. Like human impostors, they are by such means frequently able to live, thrive, and perpetuate their kind. But all depends upon not being found out; there must be many Mr. Pickwicks and few Sherlock Holmes. To believe that a gradual mimicry can slowly arise by the process of natural selection which shall be anything but a very partial defence of the eatable from the eaters, is to imagine our most intelligent and civilized communities capable of being made invulnerable from the depredations of thieves and swindlers. An example is afforded by the colour of the Common Hare. Prof. Poulton makes much of this. He remarks: "It would be hardly possible to meet with a better example of protective colouring and attitude than that of the Hare as it sits motionless, exactly resembling a lump of brown earth, for which indeed it is frequently mistaken."[409] But the protection thus assumed appears to be founded on partial observation. To a casual evolutionist in search of evidence, whose knowledge of the animal is not intimate, and whose pursuit of the same is a chase not sharpened by necessity, the Hare affords illustrative importance. But let a sportsman, a poacher, or a farmer speak on the subject, and the whole conclusion vanishes. Jefferies may at least be quoted as a good and careful observer:—"It is not easy to distinguish a Hare when crouching in a ploughed field, his colour harmonises so well with the clods, so that an unpractised eye generally fails to note him. An old hand with the gun cannot pass a field without involuntarily glancing along the furrows made by the plough, to see if their regular grooves are broken by anything hiding therein." .... "If you watch the farmers driving to market, you will see that they glance up the furrows to note the workmanship and look for game; you may tell from a distance if they espy a Hare, by the check of the rein and the extended hand pointing."[410] Though the American Hare has the colour of its pile turned grey in winter, it is still much persecuted by the Great Virginian and Snowy Owls, "which prey extensively on the animal, keeping it in a constant state of dread, especially during winter, when, in common with other rodents, it seeks to evade the stoop of rapacious birds by diving instantly headlong into the snow, thus escaping them, but ensuring destruction by man, and such animals as the Fisher-cat and Lynx, who can easily dig it out."[411] It must not be overlooked that many zoologists and evolutionists estimate the survival of the Hare as due to the protection acquired by their speed, the animals having lived under conditions in which only the swift could escape the attacks of their enemies. Besides this aspect, the animal trusts to its highly developed cunning. Mr. Kearton, a good and practical observer, writes:—"When Hares are going to seek their day or sleeping quarters, they practise a very ingenious trick in order to mislead and baffle their enemies. This consists of travelling for some distance in a direction they have no intention of pursuing, and then doubling back exactly along their own track for a good way, and suddenly leaving it by making a tremendous sideward bound to right or left. This being accomplished to their satisfaction, they trot off at right angles to the path they have just left, and go to their forms."[412] The Hare itself seems to be well aware that the safety gained by colourconcealment is very precarious. The poet Somerville knew this.

"So the wise Hares
Oft quit their seats, lest some more curious eye
Should mark their haunts, and by dark treacherous wiles
Plot their destruction."—('The Chase,' Book II.).[413]

The test of protection is concealment from the keen search of enemies, not merely an assimilative process, as noted by casual observers. Of course a partial concealment is a partial protection, but it is difficult to see how this applies to the Hare, and in the Transvaal, where most of these lines were written, I found it as foolish an animal, and one as easy to discover and shoot, as in England. Dietrich de Winckell, who according to Prince Kropotkin "is considered to be among the best acquainted with the habits of Hares, describes them as passionate players, becoming so intoxicated by their play that a Hare has been known to take an approaching Fox for a playmate."[414] Describers are often carried away by their enthusiasm for the theory of mimicry and give their pens great licence. Thus, Dr. Meyer, speaking of the neighbourhood of Kilima-njaro, writes: "The insects, too, have their 'magic mantle' of invisibility. No wonder it is difficult to make a collection, when the Butterflies and Crickets look like leaves and dry blades, the Cicadæ like leaf-stems, the Spiders like thorns, the Phasmodeæ like bare twigs, the Beetles like stones and bits of earth, the Moths like mosses and lichens."[415] Much, very much, has been made of the mimetic resemblance of the upper surface of Flatfishes to the bottom on which they rest. Mr. C.L. Jackson has given the result of a most interesting experiment he made by placing a number of small Flatfish in a tank which contained ten or twelve large Cod averaging fully twenty pounds weight each. These at once dashed after the Flatfish, "which instantly covered themselves with sand and apparently disappeared. The Cod, however, knew better. They commenced to hunt for them, carefully and systematically quartering their ground as a well-trained pointer would do, and affording a beautiful illustration of the use of the curious 'beard' possessed by many members of the Cod family. By-and-by, one of them, by means of this feeler, detected one of the youngsters and put it up. Away it went, full speed, followed by one, two, or three of the huge monsters. No Greyhound fancier ever saw a better bit of coursing as the little chap doubled and turned with the greatest agility, while over and over again the great lumbering Cod overshot their mark, and the little fish went to earth, only, however, to be again routed out and hunted until not one was left."[416]

The theory of mimicry is probably the still imperfect recognition of a great truth which is struggling to survive a mass of more or less irrelevant evidence too frequently offered in its support. It has long been regarded as an unconscious registration of a preservative action of Natural Selection; it is here suggested that it is largely an act of conscious animal volition. Whatever view be held, this alone is certain, that the theory in either its demonstrated or suggestive enunciation has been the means of a vast record of facts pertaining to the life-histories of animals and plants which would otherwise have remained either unobserved or disregarded.

 

  1. In the years to come, when we shall be estimated only as advanced teleologists, science may probably have solved the problem of animal colouration. When that is effected, who dare say that the inductive process will be unable to exhibit the long past in varied and tinted landscape on the walls of the museum, where now osteology only holds her cold and partial sway?
  2. Mr. Sedgwick is of opinion that there is much to be said for the view that the greater part of evolutionary change had already taken place in pre-Cambrian times before the fossiliferous period. "If this view was correct—and the probability of it should be borne in mind—the main part of the evolution of organisms must have taken place under totally different conditions to those now existing, and must remain for ever unknown to us." (Proc. Fourth Internat. Congr. Zoology, Cambridge, 1898, p. 75.)
  3. 'Darwinism,' p. 202.—Mr. Skertchley distinguishes "protective resemblance" as copying stationary objects, and "mimicry" as simulating moving ones (Ann. & Mag. Nat. Hist. ser. vi. vol. iii. p. 478).
  4. Some Phasmas vary in colour in the same species, as noticed in Mauritius. Cuvier was not unobservant of these peculiarities, as, referring to the Phasma rossia, from the South of France, he describes it as either of a yellow-green or greyish brown. (Quoted by Nicholas Pike, 'Sub-Tropical Rambles,' p. 164.) It is interesting to note a superficial parallelism in structure in the Skeleton-Shrimps (Caprellidæ) with the Phasmidæ, and in Mantis-Shrimps (Stomatopoda) with the Mantidæ, of which a good example may be found in the Squilla mantis, Rondel.
  5. 'Contributions to the Theory of Natural Selection,' p. 64.
  6. 'Tropical Africa,' 4th edit. p. 173.
  7. 'Tropical Nature,' p. 93.—In North America "Walking-sticks (Diapheromera) are eaten by the Crow-Blackbird and two species of Cuckoos."—S. D. Judd (American 'Naturalist,' vol. xxxiii. p. 462).
  8. "Descriptions of Fifty-two New Species of Phasmidæ" (Trans. Linn. Soc. vol. xxv. p. 323).
  9. 'Origin of Species,' 6th ed. p. 182.
  10. Zoologist,' 3rd ser. vol. xviii. pp. 291-2.
  11. Heilprin, 'Geograph. and Geol. Distr. of Animals,' p. 150.—Pharnacia serratipes, from Borneo, the largest known species, is stated by Mr. Kirby to measure nearly thirteen inches from the front of the head to the extremity of the abdomen (Trans. Linn. Soc. vol. vi. (2nd ser.) p. 448).
  12. 'Cambridge Nat. Hist.' vol. v. p. 276.
  13. In 'Zool. Results of Arthur Willey Exped.' pt. i. p. 78.
  14. 'Evolution and Taxonomy.'—'The Wilder Quarter-Century Book,' p. 56.
  15. 'Collected Essays,' vol. viii. p. 297.
  16. 'Bull. U.S. Geol. Surv.' No. 124, pp. 30-1 (1895).
  17. 'History of Creation,' 4th ed. vol. ii. p. 123.
  18. 'Text-Book of Geology,' pp. 724-5.
  19. Scudder, "Syst. Rev. Pres. Knowl. Foss. Ins." (Bull. U.S. Geol. Surv. No. 31, p. 49 (1886)).
  20. This seems to be the current statement based on present knowledge; but, as Huxley has observed, analogy seems to be rather in favour of, than against, the supposition that Amphibia and Reptilia, or even higher forms, may have existed, though we have not yet found them in the Devonian epoch ('Collected Essays,' vol. viii. p. 385).
  21. The oldest known bird—Archæopteryx—comes from the Solenhofen Limestone in the Upper Jurassic series—a rock which has been especially prolific in the fauna of the Jurassic period (A. Geikie, 'Text-Book of Geology,' 2nd edit. p. 783).
  22. 0.C. Marsh, 'Sixteenth Ann. Rept. U.S. Geol. Survey,' p. 147 (1896).
  23. 'Collected Essays,' vol. iv. p. 85.
  24. 'Collected Essays,' vol. ii. p. 354.
  25. 'The Study of Animal Life,' 2nd edit. p. 258.
  26. 'Roy. Nat. Hist.' vol. v. p. 8.
  27. 'Hist. of British Fossil Mammals,' p. xxv.
  28. 'Geographical Journal,' vol. vii. p. 295.
  29. These birds were, however, probably most divergent from present avian types. Such an example is the Archæopteryx of the Jurassic or Oolitic epoch, which was not only furnished with teeth, but had a long tapering tail, with other indications of reptilian affinity.
  30. T.G.B., reviewing in 'Nature' (vol. xlix. p. 196), 'Some salient Points in the Science of the Earth,' by Sir J.W. Dawson, speaks of the larger reptiles crawling over the soft mud, and leaving tracks in the coal-fields of Nova Scotia, and remarks: "These discoveries came as a complete surprise to the scientific world in days when few or no reptiles were known of earlier date than the Permian."
  31. 'Nat. Condit. of Existence as they affect Animal Life,' p. 126.
  32. Prof. Semper's definition of the "optimum temperature" seems to be contained in the following sentence:—"The interval between the daily extremes may be great or small without any alteration in the daily meteorological mean; moreover, the favourable temperature—the optimum of temperature for the animal—may either coincide with the meteorological mean, or lie nearer to one of the extremes—the maximum or minimum—than the other."
  33. 'Catalogue of Orthoptera in the Brit. Museum's Coll.' Pt. i. Phasmidæ (1859).
  34. "Descriptions of Fifty-two New Species of Phasmidæ" (Trans. Linn. Soc. vol. xxv. p. 323).
  35. Our knowledge of pre-Carboniferous insects is limited, but present knowledge goes to prove that a considerable insect-fauna existed in more ancient times. Thus, as Mr. Comstock has observed:—"Of Devonian insects we know several.... These differ among themselves to such an extent that we are forced to conclude, without taking into account the two known Silurian insects, that already at that early time there was a large and varied insect-fauna, of which the more primitive forms have not been discovered" ('Evolution and Taxonomy—The Wilder Quarter-Century Book,' p. 55).
  36. S.H. Scudder, 'Bull. U.S. Geol. Surv.' No. 124, p. 30 (1895).
  37. Louis Robinson, 'Wild Traits in Tame Animals,' p, 150.
  38. 'Life, Letters, and Journals of Chas. Lyell,' vol. i. p. 468.
  39. "In the earlier periods of the earth's history, reptiles were no doubt the principal enemies with which butterflies had to deal" (Beddard, 'Animal Coloration,' 2nd edit., p. 211).
  40. 'Cassell's Nat. History,' vol. iv. pp. 379-80.
  41. Among the slow Lemurs or Galagos we find enemies of the Phasmidæ. Mr. Lydekker, though not giving his authority, writes: "Some of the smaller species will readily devour Locusts, and the peculiar leaf-like Mantides, or praying insects" ('Royal Nat. Hist.,' vol. i. p. 223); but as no fossil lemuroid forms are at present known anterior to tertiary times, these records do not affect our enquiry.
  42. "The First Voyage round the World by Magellan" (Hakluyt Society).
  43. Preface to the 'Museum Regis Adolphi Friderici,' transl. by Jas. Ewd. Smith (1798).
  44. 'The Naturalist in Nicaragua,' p. 19.
  45. L.F. de Pauw, 'Bull. Soc. Anthrop. Bruxelles,' 1894, p. 140.
  46. 'Across Thibet,' vol. ii. p. 64.
  47. 'Eight Months in an Ox Waggon,' p. 174.
  48. J. Barrow, 'Travels in the Interior of Southern Africa,' vol. i. p. 53.
  49. 'Badminton Magazine,' vol. ii. pp. 840-1.
  50. Guillemard, 'Cruise of the Marchesa,' 2nd edit. p. 68.
  51. Ibid. p. 76.
  52. Ibid. p. 88.
  53. 'Nat. Hist. Selborne,' Harting's edition, p. 96.
  54. Ibid. p. 97, note.
  55. 'The Naturalist in La Plata,' pp. 60 and 71.
  56. C. J. Cornish, 'Animals of To-day,' p. 235. For other instances of changed diet, cf. ibid. p. 185.
  57. 'Royal Nat. Hist.,' vol. ii. p. 93.
  58. 'American Naturalist,' Sept. 1884.
  59. 'Origin of Species,' 6th edit. p. 138.
  60. Lydekker, 'Roy. Nat. Hist.,' vol. ii. p. 411.
  61. "In California it has forgotten how to burrow" (C.J. Cornish, 'Wild England of To-day,' p. 189).
  62. Writer in the 'Times'; quoted in 'Spectator,' January 4th, 1896.
  63. Lydekker, loc. cit. vol. iii. p. 125.
  64. Brehm, 'From North Pole to Equator,' p. 75.
  65. Ibid, editor, note, p. 567.
  66. S. Schonland, 'Zoologist,' 4th ser. vol. i. p. 155.
  67. A. Leith Adams, 'Naturalist in Nile Valley and Malta,' p. 47.
  68. Rev. M.G. Watkins, 'Longman's Magazine,' February, 1886.
  69. 'Zoologist,' 4th ser. vol. i. p. 106.
  70. S. Schonland, loc. cit. vol. i. p. 155.
  71. Loc. cit. vol. i. p. 253.
  72. Wm. Wilson, Jun., 'Investigations into Applied Nature,' p. 44.
  73. 'Darwinism,' p. 75.
  74. 'Zoologist,' 3rd ser. vol. xix. p. 293; also cf. Godfrey ('Zoologist,' 1898, pp. 216–17). Another New Zealand Parrot (Strigops habrobtilus) has lost its power of flight, and lives in burrows or other natural cavities when not abroad.
  75. Hon. Cecil Baring and W.R. Ogilvie Grant ('Zoologist,' 3rd ser. vol. xix. p. 403).
  76. 'Origin of Species,' 6th edit. p. 141.
  77. A.R. Wallace, 'Darwinism,' p. 108.
  78. G. Clunies Ross, 'Natural Science,' vol. viii. p. 190.
  79. 'Sketches of British Sporting Fishes,' p. 127.
  80. Cf. Brooks, 'The Foundations of Zoology,' p. 57.
  81. Eimer, 'Organic Evolution,' Eng. transl., p. 108.
  82. Badenoch, 'Romance of the Insect World,' p. 45.
  83. A.E. Butler, 'Our Household Insects,' p. 25.
  84. R.J. Pocock, 'Roy. Nat. Hist.,' vol. vi. p. 52.
  85. 'Modern Classification of Insects,' vol. ii. p. 541.
  86. 'Travels in the Interior of Southern Africa,' vol. i. p. 360.
  87. Ratzel, 'History of Mankind,' vol. i. p. 337.
  88. Ibid. p. 361.
  89. Kerner and Oliver, 'Nat. Hist, of Plants,' vol. i. p. 70.
  90. Cf. Wollaston and other observers, 'Zoologist,' vol. i. p. 201; vol. iii. pp. 943, 1035, 1038.
  91. 'Petites Nouvelles Entomologiques.'
  92. Gordon Cumming as early as 1850 drew attention to "mimicry" or "protective resemblance" among insects. He did not use the terms, but clearly described the facts. 'Five Years' Hunting Adventures in South Africa' (Compl. Pop. Edit.), p. 132.
  93. This word is now becoming not uncommon in general literature, and its original meaning—at least as used in biology—will tend to become obscured. Thus Max Nordau writes of "the religious mimicry of the French bourgeoisie, which was to make them resemble the old nobility" ('Degeneration,' p. 113).
  94. 'Tropical Africa,' 4th edit. p. 162.
  95. 'Tropical Africa,' 4th edit. p. 180. A similar opinion was expressed by the late Fras. Pascoe: "It is not likely that animals whose lives depend on their sight should be easily deceived; though with our mostly unobservant eyes a green caterpillar on a green leaf may easily escape notice" ('A Summary of the Darwinian Theory of the Origin of Species,' p. 13).
  96. C.G. Barrett, 'The Lepidoptera of the British Islands,' vol. iii. p. 330.
  97. 'In the Guiana Forest,' p. 48.
  98. Tennyson was an acute observer of nature. He once asked Miss Thackeray to notice whether the Sky-Lark did not come down sideways on the wing. (W.J. Dawson, 'The Makers of Modern English,' 3rd edit. p. 182.)
  99. My friend Dr. Percy Kendall, then at Barberton in the Transvaal, a most enthusiastic and successful collector, in reply to my expressed wish that he would still keep a sharp look-out for Phasmidæ, replied: "I am keenly on the look-out for them, and will in most cases back my eyes against almost any kind of insect protective resemblance dodges."
  100. 'Entomol. Month. Mag.,' ser. 2, vol. vi. p. 85.
  101. 'Curiosities of Nat. Hist.,' pop. edit., 2nd ser. pp. 97–8.
  102. Eimer, 'Organic Evolution,' Eng. Transl., pp. 235–6.
  103. John Watson, 'Poachers and Poaching,' p. 270. "A new trap catches more than a better old one until the animals have learned to understand it, and young animals are trapped more easily than old" (Prof. Tyler, 'The Whence and the Whither of Man,' p. 119).
  104. Heyn and Stallybrass, 'The Wanderings of Plants and Animals,' p. 402.
  105. How different are the theological or teleological views of the Middle Ages to the scientific conception of the struggle for existence as held to-day. We can no longer apostrophize the order Aves in the delightful utterances of the good and saintly Francis of Assisi:—"Brother birds, you ought to praise and love your Creator very much. He has given you feathers for clothing, wings for flying, and all that is needful for you. He has made you the noblest of His creatures; He permits you to live in the pure air; you have neither to sow nor to reap, and yet He takes care of you, watches over you and guides you" ('Life of St. Francis of Assisi,' by Paul Sabatier, Eng Transl., pp. 176–7). Rather now we see

    "The grub eats up the pine,
    The finch the grub, the hawk the silly finch."

  106. 'Zoologist,' 3rd ser. vol. xviii. pp. 44–5
  107. 'Lectures on Heredity,' &c. Eng. Transl. 2nd edit. vol. i. p. 17
  108. 'Zoologischer Anzeiger,' xvii. no. 454; summarized in 'Nature,' vol. l. p. 553.
  109. 'Cassell's Nat. Hist.' vol. vi. p. 205; also cf. W.B. Lord, 'Crab, Shrimp, and Lobster Lore,' p. 95.—According to Bertram, 'As a general rule, the great bulk of Lobsters are not much more than half the size they used to be' ('The Harvest of the Sea,' p. 274).
  110. L.C. Miall, 'Nature,' vol. liii. p. 154.
  111. Cf. Thomson, 'The Study of Animal Life,' 2nd edit. p. 43.
  112. Ibid. p. 48.
  113. "There is not a living creature," said Mr. Francis Francis, "which inhabits the waters which does not prey more or less on Trout ova." ("The Trout" (Fur, Feather, and Fin Series), p. 171.)
  114. The number of eggs produced by this fish has been given as much greater by more recent writers. "Upwards of two hundred and eighty thousand have been taken from a fish of half a pound in weight" ('Royal Nat. Hist.' vol. v. p. 336).
  115. 'Life of Frank Buckland,' by G.C. Bompas, 2nd edit. p. 252.—"A Turbot of 8 lb. carries 300,000 eggs; a Sole of 1 lb. 130,000 eggs" (Ibid. p. 263).
  116. It has been suggested that the greatest loss to the succeeding generation takes place at the very earliest stage of the egg, in that a large proportion of the ripe eggs discharged in the water are not fertilized by the spermatozoa, and hence perish (Mcintosh and Masterman, 'The Life-Hist. Brit. Marine Food Fishes,' p. 236).
  117. 'Audubon and his Journals,' vol. ii. p. 422.
  118. 'Cassell's Nat. Hist.' vol. v. p. 59.
  119. G. Lindesay, 'Fortnightly Review,' November, 1894.—Codfish are also infested with parasitic Copepoda. According to Surgeon Bassett-Smith, it is rare to find a fairly grown Cod without being able to take many specimens of the small semitranslucent Anchorella uncinata attached to the folds about the lips and in the gill-cavity. In its mouth and on the palate will be seen frequently half a dozen specimens of Caligus curtus; on the gills, deeply embedded, a Lernea branchialis, and on the body sore places where a number of Caligus müllleri have been fixed. And, although this investigator con- siders that in the great majority of cases these parasites are not prejudicial to the life of the fish, he describes Lernea branchialis as a certain exception to the harmless rule (Ann. & Mag. Nat. Hist. 6th ser. vol. xviii. pp. 9 and 10).
  120. Cf. J.M. Mitchell, 'The Herring, its Nat. Hist, and National Importance,' p. 37.
  121. 'Life of Frank Buckland,' by G.C. Bompas, 2nd edit. pp. 313–14.
  122. 'Das Leben des Meeres,' p. 182.—Cf. Marsh, 'Man and Nature,' p. 120, note.
  123. The excessive spermatozoa of the Herring sometimes whitens the water for scores of square miles (Matthias Dunn, 'Contemp. Rev.' lxxvi. p, 200).
  124. Thomas Watson, 'Poachers and Poaching,' p. 165.
  125. 'The Life of a Severn Salmon,' p. 7.
  126. 'The Life of a Severn Salmon,' p. 11.
  127. 'Cruise of the Marchesa,' 2nd edit. p. 68.
  128. Ibid. p. 73.
  129. Ibid. p. 92.
  130. John Watson, 'Sketches of British Sporting Fishes,' pp. 3–4.
  131. 'Royal Nat. Hist.' vol. v. p. 514.
  132. Cf. H. Woodward, 'Cassel's Nat. Hist.' vol. v. pp. 161 and 166.
  133. 'Curiosities of Nat. Hist.' Pop. edit. vol. i. p. 69.
  134. Ibid. p. 70.
  135. Wells and Davies, 'Text-Book of Zoology,' p. 128.
  136. Lydekker, 'Roy. Nat. Hist.' vol. iii. p. 126.
  137. 'Nat. Hist. Aquatic Insects,' p. 18.
  138. F.O. Pickard-Cambridge, 'Roy. Nat. Hist.' vol. vi. p. 17.
  139. Cf. A.E. Shipley, 'Cambridge Nat. Hist.' vol. ii. p. 162.
  140. Kerner and Oliver, 'Nat. Hist. Plants,' vol. ii. p. 878.
  141. Of course it is not suggested that all fish survive through fecundity alone. The European Goby (Latrunculus pellucidus) and the Sea-Stickleback (Gastrosteus spinachia) have apparently been proved to die within a year of their birth. In these cases other protection seems to be afforded. According to Dr. Günther, the fish spawns in June and July. In April the males lose the small teeth, which are replaced by very long and strong teeth, the jaws themselves being stronger. The teeth of the females remain unchanged. In July and August all the adults die off ('Introd. Study Fishes,' p. 487). In this case the male may defend the progeny. G. spinachia is, on the same authority, a "nest builder, choosing for its operations especially the shallows of brackish water which are covered with Zostera." (ibid. p. 507).
  142. 'Journal of Mental Science,' April, 1898.
  143. 'Animal Coloration,' 2nd edit. p. 29.
  144. C.W. Tait, 'Entomologist,' vol. xxvii. p. 52. (The author's name by a misprint appears as W. C. Mit.)
  145. That birds do destroy Cicadas is a fact well known. Mr. Blanford found the Accipiter Nisus sphenurus, in Abyssinia, "living on Cicadæ" ('Obs. Geol, and Zool. of Abyssinia,' p. 295). Cf. also Swinton ('Insect Variety,' p. 21); Belt ('Naturalist in Nicaragua,' p. 230); Hudson (Trans. N. Zeal. Instit. vol. xxiii. p. 20); Riley ('Science,' v. p. 521).
  146. 'Zoologist,' 4th ser. vol. i. p. 516.
  147. 'Life of Frank Buckland,' by G.C. Bompas, 2nd ed. pp. 56–7.
  148. 'Animal Coloration,' 2nd edit. p. 6.—According to Prof. Miall, the colour of the larva of Chironomus is due to a blood-red pigment, which is identical with the hæmoglobin of vertebrate animals, and "only such Chironomus larvæ as live at the bottom and burrow in the mud possess the red hæmoglobin" ('Nat. Hist. Aquatic Insects,' p. 130).
  149. 'Illustrated London News,' February 10th, 1894.
  150. 'Organic Evolution,' Eng. Transl., p. 118.
  151. 'Ornithology in relation to Agriculture and Horticulture' (1893), p. 139.
  152. Cf. Gurney, 'Trans. Norf. and Norw. Nat. Soc.,' vol. vi. p. 259.
  153. 'Wild Life in a Southern Country,' p. 147.
  154. 'Butterflies and Moths' (British), p. 144.
  155. F.O. Pickard-Cambridge, 'Roy. Nat. Hist.,' vol. vi. p. 80.
  156. J.C. Rickard, ' Entomologist,' vol. xxix. p. 170.
  157. Cf. Dixon, 'The Migration of Birds,' 2nd edit. p. 54.
  158. Kerner and Oliver, 'Nat. Hist. Plants,' vol. i. p. 682.
  159. 'The Ascent of Man,' pp. 310-11.
  160. The term "mimicry" is often considered as first applied in nature by its great enunciator, H.W. Bates. Some years ago I pointed out ('Rhopalocera Malayana,' p. 33, note) that Henfrey in 1852 had already used the term in connection with botany. Mr. Scudder subsequently ('Butterflies E. U. States and Canada,' vol. i. p. 710) showed that Kirby and Spence had anticipated Henfrey in 1815. Boisduval also, in 1836, drew attention to the phenomena (cf. Coe, 'Nature versus Natural Selection,' p. 161).
  161. 'Philosophical Dialogues and Fragments,' Eng. Transl., p. 5.
  162. 'A Naturalist among the Head-hunters,' p. 70, note.
  163. 'Habit and Instinct,' p. 52.
  164. 'Curiosities Nat. Hist.,' pop. edit., vol. i. pp. 42–3.—According to Mr. Pocock, and as a result of an experiment, a Spider treats both Bee and Eristalis with the same caution when found in its web ('Roy. Nat. Hist.,' vol. vi. p. 62). That the Bee has no special immunity is attested by Mr. Pickard-Cambridge, who states that another hymenopterous insect, Philanthus triangulum, in its larval condition feeds upon the Honey Bee. "Since at least five Bees are provided for each larva, the havoc caused in hives where these insects abound must be considerable " (ibid. p. 36). The Horse Bot Fly (Gastrophilus equi) also resembles the Honey Bee in size, colour, and form, but protective mimicry here seems an altogether unwarranted assumption, as the larval fly is parasitic in the alimentary canal of the Horse.
  165. 'Descrip. Catalogue Spiders of Burma,' Introd. p. xiii.
  166. According to Prof. Miall, when writing on 'Flies with Aquatic Larvæ,' "The attitude, the mode of breathing, and the mode of feeding observed in the larva of Dixa are curiously like those of a certain Gnat larva, Anopheles. So close is the resemblance, that an experienced entomologist has, in a published paper, mistaken one for the other. There are few better examples of adaptive resemblance" ('Nat. Hist. Aquatic Insects,' p. 163). But the reasons why this should be considered as adaptive resemblance are not stated.
  167. Cf. Steedman, 'Wanderings and Adventures in the Interior of Southern Africa,' vol. ii. p. 97.
  168. 'Zoologist,' 3rd ser. vol. xix. pp. 340–1.
  169. 'An Essay on Classification,' p. 10.
  170. 'An Essay on Classification,' p. 228.
  171. W.F. Kirby, 'A Handbook to the Order Lepidoptera,' vol. iv. p. xxiv.
  172. "Organic Colour," 'Science,' June 16th, 1893.
  173. 'Animals of To-day,' p. 165.
  174. Guppy, 'The Solomon Islands,' p. 316.—Hylodes martinicensis affords another instance (cf. Mon. Berl. Ac. 1876, p. 714).
  175. 'The Whence and the Whither of Man,' p. 164.— It is only fair to add that this is a book written by an American Professor of Biology, consisting of a series of Morse Lectures delivered at a "Union Theological Seminary," on the agreement that the subject of the lectures was to have to do with "The relation of the Bible to any of the Sciences."
  176. Opening Address, Sect. Zoology, Brit. Assoc. Ipswich, 1895.
  177. 'Origin of Species,' 6th edit. p. 158.
  178. Vol. vi.
  179. This is a direct contradiction to the testimony of Mr. Furneaux (cf. ante, p. 328).
  180. O.H. Latter, 'Natural Science,' vol. vi. p. 151.
  181. Of course by this term is meant what has been or can be demonstrated, and hence a careful observation made by a competent traveller must be accepted as decisive, for we can neither all visit the scene of the occurrence nor, if we could, is it certain we might meet with the instance. A remark by Lecky is apposite:—"If anyone in a company of ordinarily educated persons were to deny the motion of the earth, or the circulation of the blood, his statement would be received with derision, though it is probable that some of his audience would be unable to demonstrate the first truth, and that very few of them could give sufficient reasons for the second" ('Rationalism in Europe,' vol. i. p. 9).
  182. This method is not to be despised, as Lord Acton has well observed:—"Method is only the reduplication of common sense, and is best acquired by observing its use by the ablest men in every variety of intellectual employment. Bentham acknowledged that he learnt less from his own profession than from writers like Linnæus and Cullen; and Brougham advised the student of Law to begin with Dante. Liebig described his 'Organic Chemistry' as an application of ideas found in Mill's 'Logic,'" &c. ('A Lecture on the Study of History,' p. 53.)
  183. 'A Naturalist in the Transvaal,' p. 65.
  184. Cf. J.A.S. Bengal (Nat. Hist.), vol. lxiv. pp. 344-56; and vol. lxv. pp. 42-8.
  185. 'Colour in Nature,' pp. 161-2.
  186. 'Proc. Roy. Soc' lvii. pp. 5 and 6 (1894).
  187. 'The Naturalist in Nicaragua,' p. 19.—Prof. S.D. Judd, who has made a special study of the subject, records an observation to be remembered:—"I am surprised to find that Grasshoppers (Acrididæ and Locustidæ), in spite of their protective coloration, are eaten by over three hundred species of birds in the United States." ('Amer. Nat.' vol. xxxiii. p. 468.)
  188. Rös. i. v. 27. Quoted by Kirby and Spence. 'Introd. Entomol.' 7th edit. p. 413.
  189. 'Manual of Entomology,' Shuckard's transl. p. 505.
  190. 'Nature,' vol. iii. p. 166.
  191. Sir John Lubbock, 'The Beauties of Nature,' p. 156.
  192. Cf. Miss Newbigin, 'Colour in Nature,' p. 41.
  193. 'Natural Science,' vol. viii. p. 190.
  194. 'Nature,' vol. lix. p. 177.
  195. Charles Kingsley complained:—"Weak and wayward, staggering and slow, are the steps of our fallen race (rapid and triumphant enough in that broad road of theories which leads to intellectual destruction)." ('Glaucus,' p. 30.) Perhaps Kingsley would have approved of an old and summary method, as described by Gibbon:—"A Locrian who proposed any new law stood forth in the assembly of the people with a cord round his neck, and, if the law was rejected, the innovator was instantly strangled." ('Decline and Fall.') Dr. A.B. Meyer has recently remarked:—"It must be admitted that it is not very difficult to invent pleasing and clever hypotheses, specially convincing to the laity." ('Distribution of the Negritos,' pp. 81–2.)
  196. Abstract of a paper read before Morphol. Soc. 'Amer. Journ. Sci.' Feb. 1897 ('Ann. and Mag. Nat. Hist. Sixth Series, vol. xix. 354–6).
  197. 'Royal Nat. Hist.' vol. i. p. 314.
  198. 'Nat. Select, and Trop. Nature,' p. 76.
  199. 'Colours of Animals,' p. 209.
  200. 'Natural Science,' vol. vi. p. 28.
  201. Mr. Thomas informs me that the Brit. Mus. has very recently received a second specimen.
  202. 'Proc. Zool. Soc.' 1880, pp. 397–99.
  203. 'Royal Nat. Hist.' vol. i. p. 571.
  204. Ibid. vol. ii. p. 70.
  205. 'The Great Rift Valley,' p. 272.
  206. Louis Robinson, 'Wild Traits in Tame Animals,' pp. 240–1.
  207. 'Nature,' vol. li. p. 533.
  208. 'Wanderings,' Wood's edit. p. 219.—We may here refer to "the law which underlies Protective Coloration" as propounded by Mr. Abbott H. Thayer, the law of gradation in the colouring of animals, which "is responsible for most of the phenomena of protective coloration except those properly called mimicry.... Mimicry makes an animal appear to be some other thing, whereas this newly-discovered law makes him cease to appear at all." Thus "animals are painted by nature darkest on those parts which tend to be most lighted by the sky's light, and vice versâ." (Cf. 'The Auk,' vol. xiii. 1896; and reprint 'Ann. Rept. Smith. Instit.' for 1897, p. 477).
  209. Cf. 'Royal Nat. Hist.' vol. iv. p. 7.
  210. 'Royal Nat. Hist.' vol. v. p. 91.
  211. C. Lloyd Morgan, 'Habit and Instinct,' p. 12.
  212. Poulton has focussed many observations respecting instances in the Insecta, largely augmented by information received from the well-known coleopterist, C.J. Gahan. (Cf. 'Journ. Linn. Soc.' xxvi. pp. 558–612 (1898)).
  213. 'Voyage to Cape of Good Hope,' Engl, transl. 2nd edit. vol. ii. p. 16.
  214. "Must" is an unfortunate expression, and in most arguments is equivalent to "it is evident," which the late Prof. Clifford described as meaning "I do not know how to prove." ('Lectures and Essays,' 2nd edit. p. 176.)
  215. 'Biologia Centrali-Americana,' Rhynch. Homopt. vol. ii. p. 26.—Whatever we may think of this suggestion, it is at least not more improbable than some banter which lately appeared in an American entomological work by Dr. Comstock, where we read that as regards the Membracidæ, "Nature must have been in a joking mood when Tree-hoppers were developed."
  216. 'The Great Rift Valley,' pp. 273–5, and figured on coloured frontispiece.
  217. Cf. 'Zoologist,' 1898, p. 256.
  218. W.H. Hudson, 'The Naturalist in La Plata,' p. 127.
  219. Cf. Lubbock, 'Ants, Bees, and Wasps,' pp. 402–3.
  220. 'Records Australian Museum,' vol. ii. p. 91.
  221. W.J. Lucas, 'Book of British Hawk-Moths,' p. 109.
  222. Ibid. p. 113.
  223. 'The Colours of Animals,' p. 259.
  224. Hampson, 'Fauna Brit. India,' Moths, vol. i. p. 85.
  225. 'The Great Rift Valley,' p. 273.
  226. "Hanb. Order Lepidoptera," 'Allen's Natr. Libr.' vol. i. p. xxx. note.
  227. 'Royal Nat. Hist.' vol. vi. p. 26.
  228. Eha, 'A Naturalist on the Prowl,' pp. 122–3.
  229. 'The Colours of Animals,' p. 246.
  230. J.W. Tutt, 'British Moths,' pp. 61–2.
  231. Ibid. p. 91.—The italics are our own. "Practical entomologists," in the struggle for existence, and in the sense here meant, naturally includes the insect's enemies, whose sustenance depends upon their practical knowledge.
  232. 'Cambridge Nat. Hist.' vol. v. p. 265.
  233. In 'Zool. Results of Arthur Willey Exped.' pt. i. p. 78.
  234. 'Cambridge Nat. Hist.' vol. v. p. 271.
  235. Kerner and Oliver, 'Nat. Hist. Plants,' vol. i. p. 122.
  236. 'Nature,' vol. liv. p. 106.
  237. 'Sub-Tropical Rambles,' p. 162.
  238. 'Animal Life,' pp. 402–3.
  239. 'South African Butterflies,' vol. iii. p. 241, note.
  240. 'The Naturalist in Nicaragua,' pp. 314–5.
  241. 'Brazil, the Amazons, and the Coast,' p. 223.
  242. 'Slugs of Ireland,' p. 554.
  243. 'Coll. Man. Brit. Land and Freshwater Shells,' 2nd edit. p. 23.
  244. Kerner and Oliver, 'Nat. Hist Plants,' vol. i. p. 166.
    The genus Volucella comprise large flies which mimic Humble-Bees in colour and form. As observed by Mr. Pocock: "It was long supposed that the females were thus enabled with impunity to enter the nests of Humble-Bees, and lay their eggs amongst those of the proper owners." But these mimics of Humble-Bees also "visit for the same purpose the nests of Wasps, to which the flies bear no particular resemblance."
  245. Cf. Beddard, 'Animal Coloration,' 2nd edit. p. 47.
  246. 'Trans. Norf. and Norw. Nat. Soc' vol. vi. pp. 241–243.
  247. 'New Trav. Int. Parts Africa,' Engl, transl. vol. i. pp. 181–2.
  248. Cf. Layard's 'Birds of S. Africa,' Sharpe's edit. p. 783.
  249. 'Royal Nat. Hist.' vol. iv. p. 3.—It was a saying of Goethe that "there was a time when the study of natural history was so much behindhand that the opinion was universally spread that the Cuckoo was a Cuckoo only in summer, but in winter a bird of prey." ('Conversations of Goethe,' Engl, transl. new edit. p. 295.)
  250. 'Wild Life in a Southern County,' p. 252.
  251. 'Wild Life in a Southern County,' p. 265.
  252. 'Nat. Hist. Selborne' (Harting's edit.), p. 194.
  253. F.W. Gamble, 'Cambridge Nat. Hist.' vol. ii. p. 33.
  254. W. Blaxland Benham, ibid. p. 293.
  255. Sir John Lubbock. 'The Beauties of Nature,' p. 156.—On this point it may be mentioned that Father Kircher, in his Mundus Subterraneus, published in Amsterdam in 1678, "depicted the genesis of birds, apes, and men by means of the transformation of some orchids. He had been struck with the resemblance of these strange flowers to many animals, and therefore concluded that the latter were derived from the former." (Cf. Varigny, 'Experimental Evolution,' p. 14.)—Per contra, examples abound of men, who, undoubtedly authorities on their own subject, needlessly give themselves away by ludicrous comments on matters of which they are absolutely ignorant. An amusing instance of this may be found in W. Day's well-known book 'The Racehorse in Training.' The author of this book, thoroughly versed in his own business, having passed through the stages of an accomplished jockey, a successful trainer, and an astute owner, in discussing the evils of "sweating" horses, which he ascribes to "theory," points the moral of his tale by alluding to other theories, not excluding that of Mr. Darwin. We are treated to the following effusion:—"We have Mr. Darwin's theory, arising out of Lord Monboddo's idea. His lordship said over a century ago, 'that in some countries the human species have tails like other beasts, and traces Monkeys up to men.'" ('The Racehorse in Training,' 5th edit. p. 90.)
  256. Kerner and Oliver, 'Nat. Hist. Plants,' vol. i. p. 112.
  257. Ibid. vol. ii. p. 645.
  258. H.M. Ridley, 'Nat. Science,' vol. viii. p. 196.
  259. 'Introd. Study Fishes,' p. 524.
  260. 'Introd. Entomology,' 2nd edit. p. 404.—Prof. Henslow has also quite recently remarked "that there appears to be two distinct kinds of mimicry: (1) automatic and unconscious; (2) brought about by conscious action of the creature." ('Journ. Roy. Horticultural Soc' xxiii. p. 28 (1899).)
  261. W.J. Lucas, 'Book of Brit. Hawk Moths,' p. 13.
  262. Col. Pollok has suggested an excellent example of limited intelligence in the Tiger:—"All Deer possess an acute sense of smell, and against it a Tiger has to contend before he can provide his larder with game; but how does he manage it? We cannot give him the credit of the intellect of man, who, in pursuit of game, is well aware nothing can be done down wind. Were it so, not a Sambur or Deer would be left alive. The Tiger would bag them all just as he pleased,—in fact, he would then be able to kill any Deer when he wanted it." ('Zoologist,' 1898, p. 155.)
  263. 'Nature versus Natural Selection,' p. 171.
  264. 'Field,' July 29th, 1899, p. 227. Cf. also Dr. John Lowe, 'Zoologist,' 1896, pp. 1–10, as to habits of both Blackcap and Garden Warbler at Teneriffe.
  265. 'Contemporary Review,' vol. lxxvi. pp. 202–3. This observation has a distinct reference to what we previously discussed as "Assimilative Colouration," which cannot be divorced from the consideration of the theory of "Mimicry."
  266. J.G. in 'Westminster Gazette,' Aug. 10th, 1899.—A blind fish, according to the observation of Pouchet, is unable to respond to the colour of its surroundings." (Cf. Blake, 'Journ. Roy. Horticultural Soc.' xxiii. p. 24, 1899.) Prof. Henslow has given an analogous case in which the eyes of Shrimps had been covered, and the result was that "these Shrimps were not coloured like the normal ones, in imitation of their surroundings." (Ibid. p. 28.)
  267. T.B. Jefferys, 'Entomologist,' vol. xxxi. p. 241.
  268. Extr. MS. Lecture to the Bakewell U.E. Students' Association.
  269. 'Zoologist,' 1877, p. 384.—Mr. Godfrey in these pages (ante, p. 267) has also corroborated this bird's power of mimicry.
  270. 'Ornithology in relation to Agriculture and Horticulture' (1893), p. 142.
  271. 'Natural Science,' vol. vi. p. 328.
  272. 'Among Cannibals,' p. 23.
  273. W.B. Lord, 'Crab, Shrimp, and Lobster Lore,' p. 74.
  274. J.W. Tutt, 'British Moths,' p. 101.
  275. Gilbert White and Markwick, 'Nat. Hist. Selborne,' Harting's edition, p. 325.
  276. 'Personal Narrative,' Bohn's edit. vol. i. p. 377.
  277. 'The Naturalist in La Plata,' pp. 48–9.
  278. Cf. Mcintosh, 'Fifteenth Annual Report of the Fishery Board of Scotland,' p. 207.
  279. 'The Freshwater Fishes of Europe,' p. 48.
  280. Coryndon, 'Proc. Zool. Soc.' 1894, pp. 331–2.—Col. Pollok relates a similar practice of the Indian Rhinoceros (R. unicornis):—"Whilst it remains in a locality it will deposit its ordure only on one spot, and visits it for that purpose once when it commences feeding at night, and again before leaving off soon after daybreak." ('Zoologist,' 1898, p. 173.)
  281. 'Nat. Hist. Straits Magellan,' p. 109.
  282. 'Darwin and after Darwin,' vol. ii. p. 89. For further treatment on this topic, cf. same author's 'Mental Evolution in Animals,' pp. 274–285, 378–9, 381–3.
  283. This term receives no support in the best work on Birds yet written. Prof. Newton maintains that mimicry must have the prefix "unconscious," "which in every department of Zoology should be always expressed or understood"; and, again, wherever mimicry is not only possible, but even probable, "we must always remember that however produced it is unconscious." ('Dictionary of Birds,' edit. 1899, pp. 572 and 575.)
  284. Cf. Karl Semper's 'Animal Life,' p. 466.
  285. 'S. African Butterflies,' vol. i. p. 34.
  286. 'A Year in Brazil,' p. 384.
  287. 'Animals of To-day,' p. 197.
  288. 'Sci. Gossip,' new ser. vol. i. p. 10.
  289. Pres. Addr. to S. Afr. Philosoph. Soc. 1884, p. lxxiv.
  290. 'Proc. Ent. Soc. Lond.' 3rd ser. vol. i. p. 147 (1863).— Mr. Wood states that "it was remarkable also that the butterfly did not appear to be partial to the Anthriscus, except as a secure resting place, but prefered to hover over and suck the juices of the wild geranium and other flowers."
  291. H.F. Fryer, 'Ent. Month. Mag.' 2nd ser. vol. x. p. 6.
  292. 'Romance of the Insect World,' p. 217.
  293. 'Natural Science,' vol. ix. p. 299.—This is in direct contradiction to the description of the habits of another species of the genus as given by Wallace in his 'Malay Archipelago.'
  294. H.C. Dent, 'A Year in Brazil,' p. 384.
  295. 'The Eastern Seas,' p. 53.
  296. 'Essays upon Heredity,' &c, Eng. transl., vol. i. p. 287.—Weismann adds that "even this protective resemblance to or mimicry of a leaf is not perfect, for out of sixteen specimens in the collections at Amsterdam and Leyden which he examined, he could not find a single one which had more than two lateral veins on one side of the midrib of the supposed leaf, or more than three upon the other side; while about six or seven veins should have been present on each side" (ibid. p. 315).
  297. J. Watson, 'Poachers and Poaching,' p. 9.
  298. 'A Naturalist among the Head-Hunters,' p. 70, note.
  299. 'Nature,' vol. xliv. p. 451.
  300. Quoted by W. Lauder Lindsay, 'Mind in the Lower Animals,' vol. i. p. 528.
  301. 'Harvesting Ants and Trap-door Spiders,' p. 97.
  302. 'Pop. Account Travels in S. Africa,' p. 221.
  303. 'Sixth Annual Report of the Liverpool Marine Biology Committee.'
  304. 'The Journal of Marine Zoology and Microscopy,' vol. ii. pp. 101–103.
  305. Cf. Sir C. Wyville Thomson, 'The Voy. of the Challenger.'—"The Atlantic," vol. ii. p. 11.
  306. Edw. Step, 'By the Deep Sea,' p. 168.
  307. 'Life beneath the Waves,' pp. 83–4.
  308. Kerner and Oliver, 'Nat. Hist. Plants,' vol. i. p. 77.
  309. 'Cassell's Nat. Hist.' vol. vi. p. 197.
  310. Cf. J. A. Thomson, 'Study of Animal Life,' 2nd edit. p. 62.
  311. 'Natural Science,' vol. vi. p. 407.
  312. Kerner and Oliver, 'Nat. Hist. Plants,' vol, ii. p. 159.
  313. Eha, 'A Naturalist on the Prowl,' pp. 127–8.
  314. 'Introd. Entomology,' 7th edit. pp. 424–5.
  315. 'The Lepidoptera of the British Islands,' vol. iii. p. 12.
  316. Ibid. p. 89.
  317. 'The Lepidoptera of the British Inlands,' vol. iii. p. 157.
  318. Ibid. p. 195.
  319. Ibid. p. 196.
  320. Ibid. p. 277.
  321. Ibid. p. 383.
  322. 'Royal Nat. Hist.' vol. v. p. 426.
  323. L. C. Miall, 'Nat. Hist. Aquatic Insects,' p. 332.
  324. W. Furneaux, 'Butterflies and Moths (British),' pp. 31–2.
  325. 'Lectures on Heredity,' &c, 2nd edit., Eng. transl., vol. i. p. 409.
  326. 'Lectures on Heredity,' &c, 2nd edit., Eng. transl., vol. i. p. 410.
  327. C.W. Purnell, 'Phil. Instit. Canterbury, New Zealand.'—Cf. abstract in 'Nature,' vol. lii. p. 384.—The "feigning of death" among some animals, especially reptiles, may be taken as a psychological parallel to active' mimicry. Nevertheless, it has been argued that with insects this process is a "purely reflex phenomenon," rather than an act of volition. Mr. Latter experimented with the Currant Moth (Abraxas grossulariata), whose powers of "shamming" are so familiar. When seized by one wing it at once feigned death, but so it also did after being decapitated, and this action was continued in response to the same stimulus during the two days that elapsed before its death ('Nature,' vol. lii. p. 543). Like Toads, Tree-frogs do not appear to touch the insects on which they prey until these begin to move ('Roy. Nat. Hist.' vol. v. p. 281). The feigning of death apparently has a protective purpose among the inferior animals. Prince Kropotkin, on the authority of Nagel, states:—"The water-beetle (Dytiscus) does not perceive the presence of animals which it preys upon within a distance of a few millimetres, so long as they remain motionless" ('Nineteenth Century,' vol. xl. p. 253). Mr. Oxley Grabham records an instance of a Grasshopper Warbler (Locustella nævia) feigning death when touched on the nest, allowing herself to be handled as if dead—"a quivering of the eyelid was all that showed she was shamming" ('Zoologist,' 4th ser. vol. ii. p. 351).
  328. 'Natural Science,' vol. ix. p. 299.
  329. 'The Solomon Islands,' p. 317.
  330. Ibid. p. 316.
  331. 'Zoologist,' 3rd ser. vol. xviii. p. 456.
  332. 'British Birds,' p. 225.—The same writer has given a vivid description of a similar habit of an Argentine Heron (Ardetta involucris), and refers to "a marvellous instinct that makes its peculiar conformation and imitative colour far more advantageous than they could be of themselves" (P.Z.S. 1875, p. 629–31).
  333. 'Wanderings in a Wild Country,' pp. 271–2; and 'Proc. Zool. Soc.' June 15th, 1880.
  334. 'Field and Forest Rambles,' pp. 175 and 176.
  335. 'Science,' vol. xxiii. p. 64.—Capt. Bendire has made a similar observation on this species (Asio americanus).
  336. 'Wild Traits in Tame Animals,' pp, 281–2.
  337. 'A Naturalist in the Transvaal,' p. 75.—Subsequently I observed how this action could become habitual without a suitable environment. I flushed a pair of Francolinus subtorquatus, one of which squatted in the same manner, but, by force of circumstances, among the short, black, and charred remains of a grass fire. Here its colour stood out in bold relief, and I easily bagged it.
  338. Cf. W. Lauder-Lindsay, 'Mind in the Lower Animals,' vol. i. p. 526.
  339. 'With Nature and a Camera,' p. 210.
  340. 'Birds in London,' pp. 99–100.
  341. 'In the Australian Bush,' pp. 145–6.
  342. 'Nat. Hist. Selborne,' Harting's edit. p. 55.—'Grant Allen, in the introduction to his own edition of White, refers to this observation as "the germ of the theory of Protective Mimicry."
  343. Ibid. p. 175.
  344. 'Darwinism,' p. 214.
  345. James Newton Baskett, 'Papers presented to World's Congress on Ornithology,' Chicago, p. 95.
  346. Richard Kearton, 'With Nature and a Camera,' p. 254.
  347. 'Poachers and Poaching,' p. 136.
  348. 'Darwinism,' p. 215.
  349. Dr. R. Williams, 'The Zoologist,' 3rd ser. vol. xx. pp. 372–3.
  350. F.A. Lucas, 'Rept. Nation. Mus.' Washington, 1891, p. 612.
  351. James Newton Baskett, 'Papers, World's Congress on Ornithology,' Chicago, p. 100.
  352. 'Short Stalks,' 2nd edit. (1893), p. 22.
  353. 'Short Stalks,' 2nd edit. (1893), p. 136.
  354. 'New Travels into Int. Parts of Africa,' Eng. transl. vol. ii. pp. 278–9.
  355. 'Curiosities of Natural History,' pop. edit. 3rd ser. p. 232.
  356. 'Explorations in S.W. Africa,' p. 387.
  357. 'Wild Beasts and their Ways,' vol. ii. p. 151.
  358. 'Five Years' Hunting Adventures in S. Africa' (compl. pop. edit.), p. 132.
  359. 'In Haunts of Wild Game,' p. 337.
  360. 'Zoologist,' ser. iv. vol. ii. p. 167.
  361. 'Five Years' Hunting Adventures in S. Africa' (compl. pop. edit.), p. 132.
  362. 'Wild Animals I have Known,' p. 193.
  363. 'Mission. Travels and Researches in S. Africa,' p. 209.
  364. Richd. Kearton, 'With Nature and a Camera,' p. 180.
  365. Cf. Lydekker, 'Roy. Nat, Hist.' vol. i. p. 500.
  366. Cf. J.A. Allen, 'Hist. N. Amer. Pinnipeds,' pp. 301–2.
  367. 'Wanderings,' Wood's edit., pp. 166–7.
  368. Sketch of the Nat. Hist. Australia,' p. 161.
  369. Weismann, 'Lectures on Heredity,' &c, Eng. transl., 2nd edit. vol. i. p. 309.—Weismann adds:—"That the chromatophores do not themselves react upon the direct stimulus of light was proved by Lister ('Phil. Trans.' vol. cxlviii. 1858, pp. 627–644), who showed that blind Frogs do not possess the power of altering their colour in correspondence with that of their environment."
  370. The true teleological definition of the term was defined by Paley: "An instinct is a propensity, prior to experience, and independent of instruction" ('Natural Theology').
  371. 'Habit and Instinct,' p. 322.
  372. 'A Theory of Development and Heredity,' p, 19.
  373. 'Flashlights on Nature,' pp. 282–3.
  374. In discussing a philosophy like that of Descartes one must not trust alone to his own impressions and reading of the philosopher, or a critic may soon be found to prove that either he has not such an intimate acquaintance with the language in which it was written as to prevent misunderstanding, or that his mind is not sufficiently attuned to escape misconception. I will therefore quote some authorities to whom these objections do not, or should not, apply. According to Dr. Martineau, Descartes taught that "the soul, i.e. the thinking principle, though united with the whole body, exercises its chief functions in the brain." "But the soul he pronounced to be exclusively human, and, in the human being, a substance entirely distinct from the body." Hence animals are automata. "All the things that you make Dogs or Horses or Monkeys do are only movements of their fear, their hope, or their joy, which can be made without any thought" ('Types of Ethical Theory,' 3rd edit. vol. i. pp. 141, 144, 145).—Prof. Mahaffy, describing Descartes' opinion on the point, and in respect to the supposition that other animals, from the likeness of their organs to ours, may have some thought, though less perfect than our own, makes him, in rejoinder, to say:—"To this I have nothing to reply, except that, if they thought as we do, they must have an immortal soul, which is not likely, as we have no reason to extend it to some animals without extending it to all, such as Worms, Oysters, Sponges, &c." Thus, as Prof. Mahaffy further remarks:—"The difficulty which the opponents of Descartes felt most strongly was the possible extension of souls to Oysters and Worms. Thus theological questions determined the questions on both sides" ('Descartes,' pp. 180 and 182). It is a relief to turn to Kenan, who describes Francis of Assisi as "far removed from the brutality of the false spiritualism of the Cartesians; he only acknowledged one sort of life; he recognized degrees in the scale of being, but no sudden interruption; like the sages of India, he could not admit that false classification which places man on one side, and, on the other, those thousand forms of life of which we only see the outside, and in which, though our eyes detect only uniformity, there may lie infinite diversity. For Francis, nature had but one voice" ('Studies in Religious History,' p. 313).
    Even Weismann may be considered no supporter of the view of animal intelligence, judging from the following remarks:—"It is usually considered that the origin and variation of instincts are also dependent upon the exercise of certain groups of muscles and nerves during a single life-time, and that the gradual improvement which is thus caused by practice is accumulated by hereditary transmission. I believe that this is an entirely erroneous view, and I hold that all instinct is entirely due to the operation of natural selection, and has its foundation, not upon inherited experiences, but upon the variations of the germ" ('Lectures on Heredity,' &c, Eng. transl., 2nd edit. vol. i. p. 92).
  375. "Bishop Butler urges that every argument by which we maintain the immortality of man is of equal validity to maintain the immortality of the lower animals" (Canon Wilberforce).
  376. W.E. Marshall, 'A Phrenologist among the Todas,' p. 125.—It is a long flight from a Toda to an Agassiz, but we may quote the opinion of that eminent and not undevout zoologist:—"Most of the arguments of philosophy in favour of the immortality of man apply equally to the permanency of this principle in other living beings. May I not add that a future life in which man would be deprived of that great source of enjoyment and intellectual and moral improvement which result from the contemplation of the harmonies of the organic world would involve a lamentable loss; and may we not look to a spiritual concert of the combined worlds and all their inhabitants in presence of their Creator as the highest conception of paradise?" ('An Essay on Classification,' p. 99).
  377. 'Blackwood's Magazine,' August, 1899, p. 228.
  378. "I believe that the spirit of man was developed out of the anima or conscious principle of animals, and that this, again, was developed out of the lower forms of life-force, and that this in its turn out of the chemical and physical forces of nature; and that at a certain stage in this gradual development, viz. with man, it acquired the property of immortality precisely as it now, in the individual history of each man at a certain stage, acquires the capacity of abstract thought" (Josh. Le Conte, 'Evolution and its Relation to Religious Thought,' p. 295).
  379. The Hon. L.A. Tollemache has contributed some original remarks on this subject:—"I sometimes think that the lower animals bear the same sort of relation to man that the Apocrypha bears to the Bible. Theologians are apt to regard the human soul and the Bible as having a right (so to speak), each in its own way, to say 'Noli me tangere' to science. The lower animals and (though in a very different manner) the Apocrypha bar such exorbitant claims. They serve as intermediate links, and thus tend to evolutionize Religion. In other words, the lower animals are half-human, just as the Apocrypha is half-Biblical" ('Benjamin Jowett,' p. 37, note).
  380. Haeckel and Gadow, 'The Last Link,' pp. 125–6.
  381. 'The Present Evolution of Man,' p. 138.
  382. 'The Trout' (Fur, Feather, and Fin Series), pp. 87–8.
  383. 'Fortnightly Review,' April, 1894.—A curious instance of intelligence in fish is given by Frank Buckland. He was told, on good authority, that the Salmon in the Seame always jump at the weir at 11 o'clock on Sunday morning when they hear the church bells ring. Of course that is not the cause of their activity, "but it so happens that on Sunday morning, the mills being shut down, the water comes down over the weirs in greater abundance than on any other day of the week; the Salmon find this out, and, like wise fish, make the best of their time in endeavouring to get over the weir" ('Life of Frank Buckland,' by Bompas, 2nd edit., pp. 156–7).
  384. 'Journ. Mental Science,' April, 1898.
  385. 'Mission. Travels and Researches in S. Africa,' p. 242.
  386. Ibid. p. 273.
  387. 'First Crossing of Greenland,' Eng. transl., new edit., p. 85.
  388. 'Voyage of the Challenger.'—The Atlantic, vol. ii. p. 103.
  389. 'In the Australian Bush,' p. 53.
  390. 'Journal,' edited by Sir J. Hooker, p. 302.
  391. 'Roy. Nat. Hist.' vol. iii. p. 414.
  392. Sir S. Baker, 'Wild Beasts and their Ways,' vol. i. p. 180.
  393. 'Field and Forest Rambles,' p. 150.
  394. 'New Guinea,' vol. ii. p. 329.
  395. 'Organic Evolution,' Engl. transl. p. 227.
  396. 'Twenty-five Years in a Waggon,' pp. 88-9.
  397. 'Wanderings and Adventures in Int. S. Africa,' vol. i. p. 154.
  398. Quoted by J. Croumbie Brown, 'Hydrology of S. Africa,' p. 184.
  399. Ibid. p. 186.
  400. 'Badminton Mag.' vol. ii. p. 582.
  401. Cf. Viscount Ebrington, in 'Red Deer' (Fur and Feath. Ser.), p. 245.
  402. Cf. Eimer, ' Organic Evolution,' Engl, transl., p. 237.
  403. Bennett, 'Gatherings of a Naturalist in Australia,' p. 23.
  404. 'Audubon and His Journals,' vol. ii. p. 44.—A delightful legend is related by Renan on this subject:—"One of the early Buddhas who preceded Sakya-Mouni obtained the nirvana in a singular way. He saw one day a Falcon chasing a little bird. 'I beseech thee,' he said to the bird of prey, 'leave this little creature in peace: I will give thee its weight from my own flesh.' A small pair of scales descended from the heavens, and the transaction was carried out. The little bird settled upon one side of the scales, and the saint placed in the other platter a good slice of his flesh, but the beam did not move. Bit by bit the whole of his body went into the scales, but still the scales were motionless. Just as the last shred of the holy man's body touched the scale the beam fell, the little bird flew away, and the saint entered into nirvana" ('Recollections of my Youth,' Engl, transl., p. 116).
  405. 'African Hunting and Adventures,' 3rd edit. p. 15.
  406. A British lepidopterist has recently remarked: "It is well known how different species of Lepidoptera differ in their habits adopted for protection, some relying on very acute vision, others on their resemblance to their surroundings" ('Entomologist,' vol. xxviii. p. 278).
  407. An observation made by that keen political and social notist, Greville, illustrates what is here meant:—"I could not help reflecting what an extraordinary thing success is in the world, when a man so gifted as Mackintosh has failed completely in public life, never having attained honours, reputation, or wealth, while so many ordinary men have reaped an abundant harvest of all. What a consolation this affords to mediocrity! None can approach Mackintosh without admiring his extraordinary powers, and at the same time wondering why they have not produced greater effects in the world, either of literature or politics. His virtues are obstacles to his success; he has not the art of pushing or of making himself feared; he is too doucereux and complimentary; and from some accident or defect in the composition of his character, and in the course of events which have influenced his circumstances, he has always been civilly neglected" ('Greville Memoirs,' 2nd edit., vol. i. p. 242). Ruskin places tact in a purer and higher plane when he describes it as "sympathy,—of quick understanding,—of all that, in deep insistence on the common but most accurate term, may be called the 'tact' or 'touch-faculty,' of body and soul: that tact which the mimosa has in trees, which the pure woman has above all creatures,—fineness and fulness of sensation, beyond reason,—the guide and sanctifier of reason itself" ('Sesame and Lilies,' edit. 1893, p. 43). Nor must we forget the advice of the old Roman courtier to Sir Henry Wotton, as related by him to Milton,—pensieri stretti, ed il viso sciolto (thoughts close, countenance open).
  408. "Some persons' eyes seem to have an extraordinary power of seeing through water, and of distinguishing at a glance a fish from a long swaying strip of dead brown flag, or the rotting pieces of wood which lie at the bottom. The ripple of the breeze, the eddy at the curve, or the sparkle of the sunshine cannot deceive them; while others, and by far the greater number, are dazzled and see nothing."—(Jefferies, 'Gamekeeper at Home.').
  409. 'Colours of Animals,' p. 67.
  410. 'Wild Life in a Southern County,' new edit., pp. 7–8.
  411. A. Leith Adams, 'Field and Forest Rambles,' p. 80.
  412. 'Wild Life at Home,' p. 114.
  413. Cf. C.C. Coe, 'Nature versus Natural Selection,' p. 184.
  414. 'Nineteenth Century,' vol. xxviii. p. 706.
  415. 'Across East African Glaciers,' p. 80.
  416. 'Lancashire Sea Fisheries,' pp. 34–5.


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