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Popular Science Monthly/Volume 35/May 1889/Correspondence

< Popular Science Monthly‎ | Volume 35‎ | May 1889



Editor Popular Science Monthly:

IN your February issue Mr. S. F. Goodrich brings up the question whether animals ever "play 'possum." He suggests that the apparent helplessness of certain animals when attacked is real; that what is popularly ascribed to cunning is in reality due to fright—a faint and not a feint.

This theory is new to the great majority of those who have observed the habit referred to; but its newness is not of itself a serious objection to it. Many familiar phenomena have waited long before receiving correct explanation. It has always been taken for granted that animals passive in the presence of danger were attempting deception. Rarely has any other explanation of their conduct been offered; but it does seem almost incredible that our far-away kinfolk should be using that distinctively human device—simulation.

Many of these acts can be satisfactorily explained on either assumption. The opossum may at times be unable to move because of his fright, or he may assume the passiveness of death as his surest hope for life. Which appears the more reasonable? Granted that it is difficult for us to credit the animals in question with sufficient intelligence and self-control to select deliberately such mode of defense, does not the other theory involve us in much greater difficulties?

Do the lower animals ever feign any condition? If this question can be answered positively, it seems to me that we shall have the solution to the other problem. The cat, when playing with a captured mouse, appears to feign unconcern and forgetfulness while looking away from its victim, and surprise on seeing it again. Probably there are very few persons who have not at least once been deceived by the disabled appearance of birds when their nests or young were approached. Very many of our birds under these circumstances act so as to draw attention to themselves, and when pursued keep just out of reach, luring the pursuer to his greatest efforts by seeming to have reached the maximum of their speed. Finally, the foolish one, with feelings injured, gives up the chase in disgust. Are the birds conscious that their appearance is deceptive? Fear certainly did not make them really helpless. If it be admitted that there is hypocrisy in such cases, then it may not seem impossible for even these stupid animals to feign other conditions, not excepting that of death.

If the opossum while in this passive state be thrown into water, its passiveness will be modified somewhat, but will still be maintained. Its nose will be kept above the surface, and it will paddle away so very gently that the motion is hard to detect. If while "dead" a stick be put into its open mouth, it will quietly close on it with its teeth, and may then be carried long distances swinging from the stick, but showing no other signs of consciousness; or it may be carried by the tail, it doing the holding. Do these facts, which none acquainted with the habits of opossums will question, sustain the theory of paralyzing fear?

The fox also appears helpless sometimes when caught, and there are instances recorded of men being severely bitten because of too much faith in its apparent innocence. The toad w hen captured frequently makes a complete surrender, closing its eyes and settling down to apparent listlessness. If everything remains quiet, its eyes will soon open very gradually, closing again if danger be still visible; if not, it will prepare to move. If the enemy be discovered while it is trying to escape, it again assumes its former submissiveness.

The actions of the spreading adder are also curious. If approached, it makes a hissing noise and starts forward, looking as hideous as possible, as though it would frighten its enemy. These motions it will repeat several times if touched with the finger or a stick; but finally it seems to despair of relief by that method, and throws itself on its back and utterly refuses to make further defense. On first observing this peculiar position, I was sure the reptile was dead; but on returning a few minutes later to the box in which I had it, found it looking all right. The same effect followed the repetition of the teasing. When I turned it right side up, it immediately turned back again. Repeated experiment since with these snakes has shown that they even resist with muscular effort a change from their unnatural position.

Many beetles have habits similar to those of the animals named, and, like them, their pretense is overdone. When the Colorado beetle, or potato-bug, falls from the potato-vine on being approached, it nearly always comes to the ground with the feet up.

Many other examples might be given; but the above, I think, are sufficient to show that the theory that in the phenomena under consideration the animals are helpless from fright is untenable. In almost every case the animal manifests consciousness, shows itself cognizant of the situation, and betrays its anxiety to escape.

H. L. Roberts.
Lewistown, Ill., February 23, 1889.


Editor Popular Science Monthly:

A short article on the "Sense of Direction in Insects," in the February number of "The Popular Science Monthly," served to remind me of an account of the travels of an ant told me by my father, the late Prof. Lyford. His attention was drawn to the insect by a very heavy load which it was carrying. When first noticed it was traveling along a gravel walk in most approved fashion, and, while occasionally avoiding a large pebble, was pursuing in the main a very straight line. But soon it turned from the walk, and taking a different direction entered a grass-plat. Here a different mode of proceeding was adopted. Finding it difficult to walk around the grass-stalks, it would climb to the top of the blade, let it bend down with its weight, then get off and climb a second, and so on. Besides making quite satisfactory progress in this manner, the top of the grass-blade seemed to furnish a convenient point of observation, like a tree-top in a forest. Through the grass the route was very direct until it reached its "hill," when it disappeared. A careful calculation of the distances traveled on the gravel and through the grass, and of its rate of progress over the two, indicated that, while the total distance was greater than if measured in a straight line, yet that the insect had actually selected, very nearly if not exactly, the route which could be traversed in the shortest time, seeming to realize that in this case at least "the longest way round was the shortest way home."

Edwin F, Lyford.
Springfield, Mass., February 20, 1889.


Editor Popular Science Monthly:

In the February number of the "Monthly," in the "Miscellany," page 572, Prof. Mendenhall's account of the Japanese "magic mirror" is quoted. The reason which he gives for the peculiar property that a few accidentally possess of reflecting upon a screen an enlarged image of the figures in relief on the back of the mirror seems to me, to say the least, questionable.

While in Japan I became intensely interested in the phenomenon, which has been explained in many ways. By the process of exclusion, all for the time being were discarded but two. The first of these is given by Prof. Mendenhall, viz., "When the mirror is cast the cooling process has the effect of drawing it slightly out of shape"; and the second endeavored to answer the question by supposing that in the casting there was produced a difference of density opposite the ornamentations, which are in decided relief. It was argued that the more dense portions would be abraded less in the operations of grinding and polishing than the softer parts, hence leaving them a very little in relief. There is no design, in the mind of the artist, for an unequal density in the casting, and, so far as I am aware, there is no proof that it exists. In observing the mode of grinding the face for the final polish, it appeared quite evident that all "drawing" and differences in density would be reduced to quite the same level. The process of final finish seemed to me to solve the puzzling riddle, which is as follows: When the moderately convex surface has been brought to a satisfactory and equable condition, the casting is placed upon a solid base, on which the figures in relief firmly rest, leaving the intervening spaces practically unsupported. In order to get all the "drawing" and unevenness out of the face of the casting, some are ground thinner than others. The final polish is given by violently rubbing the surface with the rather small end of a soft-wood stick, applied with heavy pressure. It seems evident that when the stick passes from the thick supported to the thin unsupported parts, the latter would be slightly depressed, and the continued rubbing pressure would fix these depressions, leaving slightly raised lines exactly opposite the ornamentations in relief on the back. These are so slight as not to be detected by the eye, but when cast from the convex surface on a screen at some distance the diverging rays would enlarge the image, so as to produce the fact of the phenomenon.

G. O. Rogers.
Apam, Mexico, February 1, 1889.


Editor Popular Science Monthly:

In your January number' you say, "To what extent a poisonous serpent's bite is noxious to itself is doubtful"; and the testimony of Dr. Stradling there given tends to settle the doubt in the negative. Bearing upon this question is the following from Lieutenant Michler's report to Major W. H. Emory, United States Army, and bearing date July 29, 1856. It is to be found in Major Emory's report of the "United States and Mexican Boundary Survey," vol. i, pp. 121, 122.

"The glare of our fires attracted a large number of rattlesnakes; the whole place "(the "Sierra del Poso Verde")" seemed infested with them. We judged them to be a new species from their tiger-colored skins; they were exceedingly fierce and venomous. On the deserts of the Colorado we had often seen others with horns, or small protuberances above the eyes; and Dr. Abbott has taken from the body of still another species quite a number of small ones, among which was a monstrosity with two perfectly formed heads attached to one neck. When you lie down on your blankets stretched on the ground, you know not what strange bedfellow you may have when you awake in the morning. My servant insisted upon encircling my bed with a riata of horse-hair to protect me from their intrusions. Snakes are said to have a repugnance to being pricked by the extremities of the hair. The paisano, or chaparral cock, surrounds his antagonist, while asleep, with a chain of cactus-thorns. When the preparations are all made, the bird flutters over the head of the snake to arouse it to action; the latter, in its vain efforts to escape, is irritated to such a degree by running against the barrier encompassing it, that it ends its existence by burying its fangs in its own body."

To what end or purpose is all this wonderful strategy on the part of the bird? Is it simply to imprison the snake? Is it for the fun of seeing the reptile fooled? Is it merely that the snake should "inflict only mechanical injury upon its own body" which would not be at all likely to prove fatal; or is the whole story false?

A. J. Williams,
Cleveland, Ohio, February 21, 1889.