Essay on the mineral waters of Carlsbad/Observations on the microscopic animalcules about the hot springs of Carlsbad

by August Carl Joseph Corda

OBSERVATIONS
ON THE
MICROSCOPIC ANIMALCULES ABOUT THE HOT SPRINGS
OF CARLSBAD,
BY
Mr. A. J. C. CORDA, OF PRAGUE.

 

(Translated from the German manuscript.)

 

When the celebrated Dane, Otho Frederick Müller, discovered, in 1786, the Vibrio paxillifer, and described the Conferva pectinalis, it was for the cultivators of natural history a new series of beings, whose form and life appeared so problematic, that some time elapsed before they knew to what organic kingdom they belonged. Müller had already classed the Vibrio paxillifer among animals, and the Conferva pectinalis among plants. But this sagacious observer ranged them very soon amongst the infusory animalcules. Mr. Bory de St. Vincent (Dict. class. d’histoire naturelle, art. Arthrodiées) and Mr. Nitzsch (Beiträge zur Infusorienkunde. Halle, 1817) threw later some light on their nature. The first placed them between the two organic kingdoms, and the second acknowledged their animality. After them, the celebrated traveller in Africa and Asia, Mr. Ehrenberg, author of important discoveries, ranged the animalcules, of which we are treating, among the cuirassed Infusoria with feet alternately moving in and out; and about the same time several naturalists, endowed with less perseverance and sagacity, and without recurring to analogy nor to anatomy, placed them in the vegetable kingdom. Professor Agardh, of Lund in Sweden, formed with them a family of plants, which he called Diatomeae, and ranged them in the lowest cathegory of the Algs. He was followed by MM. Lyngbye, Turpin, Meyen, Kützing and others. Greville, Meyen and Turpin gave the best representations of them; Kützing described them in his Synopsis Diatomearum (as wretched a performance as the drawings representing these animalcules), without possessing the means required for similar investigations, nor the knowledge of their remarkable structure.

Though incomplete, this short historical sketch will suffice, I hope, for the intelligence of this Memoir, in which nothing farther is intended than the natural history of the thermal animalcules, which I observed last summer (1834), about the hot springs of Carlsbad.

Springsfeld, in 1752, and Mr. Scherer, of Vienna, in 1787, were the first who wrote upon the green matter (materia viridis) of the hot waters of Carlsbad, and, after them, the celebrated algologue A. C. Agardh (Almanach de Carlsbad, for 1834, ch. IV.) described particularly the Oscillatoriae and a few Frustuliae; he repeated the same description in his Conspectus Diatomearum, of which we find again the drawings, probably taken from some entirely dried and decayed specimens, in his Icones Algar. Europ. Tab. 1—2.

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HABITATION OF THE ANIMALCULES.

An attentive observer will scarcely pass near the springs of Carlsbad (or any other hot mineral water) without remarking upon the wood and stones, which surround the wells, a limy and gelatinous green stuff, thicker or thiner, and often lamellous. Plenty of it is to be seen upon the boards, stones and pipes, which surround the hot wells, at their outlets, in short, in every place where the hot water runs or transudes. Carefully examined, that unctuous and gelatinous substance is composed of myriads of elegantly and symmetrically formed beings, most of them belonging to the animal kingdom; and their forms, their mode of life and of propagation can only excite the highest degree of astonishment.

In the middle of that chaos of limy, often stinking and putrid substances, apparently deprived of life, the eye, powerfully armed, discovers ideal proportions and symmetrical forms, which the most fecond imagination of an arabesque painter could not create. These myriads of beings are however animated, presenting, under the same type, an infinite variety of forms; these corpuscules, whose size is frequently the 0,000015, viz: the 15millionth part of a Paris inch, and seldom more than the 9thousandth part, are endowed with organs, simple indeed, if we compare them with animals of superior orders, but complicated, proportionally to their own body. They move, give signs of feelings of self-preservation and propagation, possess irritability, and often even the means of appropriating to themselves extraneous substances, foreign to their nature.

The fluid, in which they live, is originally water, in contact with inorganic matter, with heat, and with the remains of organized bodies, the dissolution of which forms a sort of animal lime. Several naturalists have taken this unctuous, transparent and gelatinous substance for parts or organs of these beings, which they classed among plants. A more attentive investigation of the mucous inferior layer of Oscillatoriae (Pl. VI.) shows, however, that the gelatinous mass is composed of the deceased animalcules, in which we can distinguish the various degrees of their dissolution, their fibrous remains, and their transition to a gelatinous form. This inferior mucous layer (the stratum mucosum of botanists), does not constitute the organs of the animalcules, though the latter cannot live and propagate themselves but in the middle of them. Nevertheless, I have often drawn them out of the gelatinous mass, in order to place them in river-water, where they lived a long time, without any appearance of diseased alteration.

Water, a solid substance, heat, a beginning putrefaction, appear indispensable to the production and propagation of the animalcules; and such conditions are in fact always united. Without moisture, they never live; a solid substance must offer a basis to moisture, and, according to physical laws, the contact of the one with the other generates heat, and only by the simultaneous action of moisture and heat can putrefaction take place.

Though often found in the froth of rivulets and rivers, they have not been generated there, but floated off by the stream. These animalcules living never in thermal water, they are only to be seen at a few inches distance from the wells, and when kept in glasses or pots, they soon retreat towards the sides of the vessel. They are never found in the limpid water of a cold spring, river or well, nor of a hot spring, even if the water has reposed for hours and days, so that we can consider as erroneous, and suggested by a fondness for marvellous things, the popular opinion, so generally spread, that we swallow with common water innumerable animalcules. Sight and smell would disgust any one to drink a water full of these living creatures, which is always dirty and coloured

In order to investigate these animal aggregations, the green gelatinous matter is collected in a glass, with a wide orifice, into which we pour a little of the water in which they lived, or, if not to be had, river-water.

The microscope, intended for these investigations, must show the magnified objects clear and distinct. MM. Pistor and Schick, in Berlin, Plössl, in Vienna, and Chevalier, in Paris, make the best instruments, which magnify 1000—3000 times. Those which magnify only 5—600 times, are unfit for such researches. A particle of the green thermal substance, of the size of a pin’s head, is placed upon the object-glass, and torn between two sharp instruments, or, if wanting, with pins; and the green fragments are moistened with a small drop of water. The observation begins with magnifying 100—200 times, in order to detect the most distinct forms. Has an animalcule been discovered, it must rest some time under the instrument. The observation must be repeated with a magnification of 4—600; and after having acquired some skill in the mode of magnifying, we continue the intended investigation.

After having acquired by numerous trials a certain dexterity, the anatomy of the animalcules takes place in two different ways. The first is plain and easy: A flat bit of glass, as thin as paper, very pure and transparent, is placed over the animalcules, which are flattened by the pressure of the glass, so long as the observation lasts. The second, requiring still more dexterity, takes place by separating the larger species, with a very sharp and cutting needle, but it requires an extremely good eye and patience.

Perseverance, so necessary in all sorts of researches, is indispensable in microscopic observations, which must be often repeated and varied; but that trouble is amply rewarded, and the pleasure felt by the investigator, who discovers new forms, so beautiful, so surprizing and unexpected, is beyond description.

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FORM AND ORGANS.

 

According to the organisation of these animalcules, we can divide them into two classes, subdivided into six families, viz, the Naviculae, the Cosmaria, Euastra, Fragilariae, Closteria and Arthrodiae. The three first families have a brittle tegument, the three others a flexible one; but, in order to recognize exactly the form of these creatures, it is necessary to describe each of the organs which compose them.

The external tegument (epidermis) of these animalcules is of two species. It is a siliceous, transparent and vitreous shell, called cuirass (lorica). (Pl. I. II. IV. V.); or, the cuirass wanting, the epidermis is naked (Pl. III. et VI.).

The cuirass, answering, in the greatest number of animalcules, to the valve of muscles, is composed of two siliceous and transparent parts, surrounding the animal. The univalve cuirass is a leaf rolled on itself (Fig. 5—17., 38—17), the edges of which are confounded together, so that they never form, except a few small openings, a valve surrounding entirely the animalcule. That cuirass appears smooth, for instance, in the Frustulia appendiculata. Ag. (Pl. I. fig. 12—13. a.), or striped, as in the Navicula costata (Pl. I. fig. 9—11.), where the stripes are distributed like rays, setting from an ombilic, to be found in one of the middle ribs of the cuirass (fig. 9. a.); or merely ribbed; or provided with strong and elevated ribs, such as in the Navicula ciliata (Pl. I. fig. 5. a.), where the ribs are besides covered with fine hair.

Towards the lower parts, the cuirass forms in the Naviculae and Frustuliae a flat surface, generally quadrangular (parallelogram), called pedal surface (fig. 8. e., fig. 13. b.), to which two animalcules are always adhering.

In the Diatomeae, for ex, in the Diatoma fenestratum (Pl. IV. fig. 38.), the cuirass is flattened on the edges, and cut in half circles, whilst, where the animalcules are adhering, it forms a narrow surface of reunion (fig. 38. b.). The form of this surface corresponds always with that of the cuirass, viz. it is narrow in the flat cuirass, and triangular in the triangular cuirass of the Desmidium Swartzii (Pl. IV, fig. 44.). The form of the bivalve cuirass is always analogous to that of the animalcule. Surirellae (for ex. the Surirella Venus (fig. 1—4.) have, according to the length of the animalcule, an open cuirass, each valve of which is like a pot, the one included in the other, in a very peculiar manner, forming a sort of inge (fig. 4. b.), nearly similar to a round snuff-box. Their edges, besides, are supplied with rounded and radiated elevations (fig. 4. A.), between which are seen furrows of the same size (fig. 4. B.). Though different, the bivalve cuirass of the Closteria has an analogous form. Each valve (fig. 61. A. A.) forms cornucopiae, the uniting point of which is seen in the middle of the animalcule, where the sexual openings (fig. 61, c.) are to be found. No inge is to be seen, but the two thin edges of the valves (fig. 62. d.) are placed immediately one upon the other. This cuirass is open at each point of a valvule, its being the place where we see the opening which I consider as the mouth (fig. 61. 63. b. b. 64. 65. a. a.)

In the Pleurosicyos myriopodus, the cuirass has two valves, of the same form as in the Closteria. It is, besides, octangular (fig. 69.), and on each side of an angle, 8—12 pedal holes (fig. 68. b.) are seen.

The Cosmaria must be considered as double animals, forming together a double cuirass, and each separately a single one.

The Cosmarium deltoïdes (fig. 18-19) has two warty cuirasses, united on their broad surface, the openings of which communicate only with the surface uniting both animalcules. The Cosmarium bipes (fig. 20) has a cuirass of the same form, and appears however always split on its external surface, the more so as, during fecondation, this fissure (fig. 20. a. a) opens itself. In the middle of the lines which unite the two cuirasses of an animalcule, we see a nearly quadrangular opening of the uniting points; which opening is the mouth. On both sides of it are two openings (fig. 20. b.), through which the animalcule pushes a scarcely perceptible bladder, by means of which it sticks to the inside of the glass. I name therefore these openings pedal holes.

In the Colpopelta viridis (fig. 28) we see, on the inferior surface of the univalve cuirass two openings (a), placed opposite one another, which must be considered as those of the alimentary tube.

I name coat the epidermis which surrounds entirely the animalcule; and, as far as I could observe it in some larger species of Naviculae, inhabitants of rivers, that coat is, at the same time, the pedal organ, which, under a vesicular form, passes through the valvular openings, and by means of these feet the animalcule adheres to the glass.

In the cuirassed animalcules (such as the various species of Surirella, Navicula, Closterium and Cosmarium), the epidermis clothes the whole internal surface of the cuirass, and lines it like a bag.

In the Surirella Venus (Pl. I. fig. 4.) the epidermis possesses manifestly muscular strength, and when the muscular bag opens itself, it opens the cuirass, and by its contraction, it closes entirely the valves.

In the Cosmarium deltoïdes (fig. 19.) the two valves of the cuirass separate themselves by the muscular strength of both bladders (a.), passing through the holes of the cuirass, and uniting themselves again, as soon as the bladders are drawn back. In the Cosmarium sinuosum (fig. 21), stellinum (fig. 22.), truncatum (fig. 23—24), as well as in the Closteria (Pl. V.), I have seen, in the very moment when the animalcule was dying under violent galvanic strokes, the coat falling off from the cuirass, and contracting itself partly. I have already said that I shall call naked the animalcules of this series, viz. the Euastra, Pediastra and Stauridia (Pl. III), the Scenodesmi (Pl. IV. fig. 49—53), the Sphaerozosmi (fig. 39), the Ophiothrix (fig. 83—84), the Sphaerodesmi (fig. 86-90), and the Oscillatoriae (fig. 71—81.). All these genera stand at the lowest degree of the animal scale, and give but weak signs of life.

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ORGANS OF MOTION.

 

Their movement is performed by very simple organs, when in possession of them, or with the whole body.

In describing the cuirass and the coat of these animalcules, I spoke of the feet passing through the holes of the cuirass, and of those which are formed by the elongation and extension of the coat. These feet are easily observed in the Frustuliae and Naviculae of larger species. The Pharyngoglossa sygmoïdea has, above the mouth, a longitudinal fissure (fig. 16. b.), through which the pedal bladder comes out (fig. 16. b. b. b.). A similar bladder is observed in the posterior part of the body, and at the end of the intestinal tube (fig. 16. c.).

In the Frustulia viridescens (fig. 17.) larger vesicular feet (b) are easily seen. In the Scalptrum (fig. 70.) they are seen (b.) near the extremities of the body upon the angles, where the middle opening is found.

In the Pleurosicyos myriopodus (fig. 68) we see several hundreds of such feet (b.); the animalcule being octangular, and each side having 18—20 such feet, consequently upon both sides 40 feet: 40 x 8 = 320 are the total number of the animal’s feet.

In the Oscillatoriae, the Closteria and several other genera, I never was able to discover these feet.

The motion of the animalcules is seldom performed by the vesicular feet. The Frustuliae and Naviculae swim by a slow motion of the whole body; the Cosmaria and Euastra, by floating; the Diatomeae, by moving every one of their limbs; and the Oscillatoriae by a vermicular creeping, similar to the motion of earth-worms. Ophiothrix derives its name from the serpentine and spiral motion, and from the quickness of this animalcule, comparatively superior to that of all the creatures of this series.

The Sphaerodesmi (fig. 85—87.) roll themselves by a floating motion, and rise by a spiral one, by means of which, though slowly, these animalcules ascend from the bottom to the surface of the water, and go down again.

The act of creeping, peculiar to several Oscillatoriae seems to be performed by pressure upon neighbouring filaments or other parts. Some of these animalcules are always seen creeping in company under the microscope.

The Oscillatoria subulata (fig. 71—72), standing upright, cannot creep with the whole body, but that remarkable creature seems to be constantly employed to its own propagation, considering that the coat of the mother opens itself again, as well as the still younger one (c. d. e.). This last filament in the place where it abandons the opening of the coat, is articulated, as well as the coloured content of the maternal filament (d.). These articular nodes are separated by filiform intervals and represent a rosary, loosing itself in its upper part into the capillary point, which is often very long, and has very thin articulations. When a filament has left by creeping the mother’s body (as in fig. 72), this content (b.) forms a point, often similar to a drop, which grows gradually longer, till it acquires the form of an articulated filament; and in this manner the process already described is successively performed.

Other Oscillatoriae (such as the Oscillatoria elegans Ag. fig. 73—74) creep in turning and bending the pointed extremity of their head (a.), from upwards downwards, or from right to left, as the movement requires.

If, during this movement, filaments or other exiguous bodies present themselves on its way, the animalcule feels them with the point of the head, till it has gone round or over them. Does it meet larger bodies, it adheres to them or ascends over them, but it very soon puts aside the smaller ones, or, as the Naviculae do, drives them along with itself.

The Frustuliae move in less than a minute, upon a surface of one line. The Oscillatoriae, in four and twenty hours, move from one to four inches.

Our Diatomeae, found in rivers, are almost motionless; those which inhabit the sea move quicker. Many animalcules of this class move only during the night. I have seen the Closterium costatum (fig. 61.) and the Closterium didymotocum (fig. 64.) ascend, during that time, from the bottom of a glass cylinder, from 4—30 lines, upon the inside of the glass, whilst, in day-time, and at the light of a lamp, I could not observe any motion.

Several Oscillatoriae creep only during the night and in dark places.

Upon many of them, as well as upon various Naviculae and Frustuliae, light exercices a manifest influence. When kept in cylindrical glasses, they move towards the lighted side, and abandon the dark one. I avail myself of this circumstance, when I want to catch the finest specimens. When preserved in china vases, filled with water, they reach very soon the surface or the sides of the water, when exposed to light.

In day-time, the Surirella Venus closes more its cuirass, which is never seen open but in dead individuals. During the night, and at the weak light of a lamp, I found many of them open, but they closed quickly their valves, when I directed upon them a more intense light.

I have very seldom seen the points of the Pediastra bending and moving themselves, and it is equally rare to see the Closteria crooked; but these motions were much more frequent in the animalcule, when exposed to galvanic or electric strokes.

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ORGANS OF NUTRITION.

 

The act of nutrition and its organs are objects of difficult observation in this series of animalcules, on account of the impossibility of using the means employed by Mr. Ehrenberg in the investigation of the true Infusoria, because the creatures, mentioned in this inquiry, do not admit colouring substances. Analogy alone can assist us, and even very weakly, in these researches.

In the Surirellae and Naviculae I could not discover any tnbe running parallel to the body.

We see, however, in the Surirella Venus a skin separating itself from one of the points of the coat, in which skin (d. fig. 4.) there is an incision, leading to the content (e). By means of this overture, the animalcule throws out entirely the content; but I never could distinguish upon the coat any opening nor fissure.

The Naviculae, according to my classification, include the species of the most ancient genera of Frustuliae and Naviculae; which, next to the pedal surfaces (fig. 4. 8. e.), found in the axe of the body, are supplied with two openings (d. d.) leading to two empty tubes (f. f.) passing through the whole animal, and, on both opposite extrmities, terminated also by two holes, near the smooth pedal surface.

In the Navicula costata (fig. 10.) these two openings are found under the flat pedal surface, and even the truncated extremities of the body (f. f.), placed on the edges of that surface. The foot (b.), resembling a scarcely perceptible wart, is to be seen in the axe of the body, between the two openings (f. f.).

The Pharyngoglossa is the only genus of this series, in which the mouth, the alimentary tube and the anus of the animalcule are clearly distinguished. The head (fig. 16. A.) is casely known by the fissure of the cuirass, out of which the superior foot (b. b.) comes. We find under this foot the orifice (a.), in which a stopple is seen (a. a.) moving in and out. From the mouth issues the cylindrical thin gut (f. f.) reaching the back parts of the body and unloading istelf into the orifice of the cuirass, through which the back foot (e. c.) protrudes.

The Pharyngoglossa is the only animalcule of that series, in which I could distinctly see an ingestion of substance. He pushed the stopple (fig. 16. a. ²) much forward, with the help of a very fine and scarcely visible ligament, out of the opening of the intestinal tube, which by analogy we shall call the mouth (a), in consequence of which I saw an empty space between the stople (a. ²) and the mouth (a. ¹). Water, saturated with organic atoms, penetrated of course this empty space, and dragged these atoms into it. Soon after, the second introduction of the stopple (a. ²) stuffed the mouth (a. ¹) and led into it, at the same time, both the water and the substances with which it was impregnated.

The various species of Cosmaria seem to receive substances through the hole (fig. 20. c.), which is constantly open. The Colpopelta has upon the inferior surface, at both extremities of the body, a longitudinal tube (fig. 28. a.), which seems to unite both openings.

In the Closteria we find upon the point of both sides of the cuirass, perforations which I consider as mouths.

In the Closterium Lunula Nitzsch (fig. 56—58.) this mouth (a.) is very easily found; it leads to a very short, and sometimes not well marked tube (b.). Moreover, we observe this orifice in the Closterium caudatum, acuminatum, didymotocum and spirale (fig. 59—67.). In the Closterium costatum each horned extremity of the cuirass is truncated, and a larger, blunt and more opened mouth (fig. 61. 63. b. b.) comes out of its edges. Between this orifice and the content of the animalcule, through which the intestinal tube passes, the Closteria present a peculiar organ, which I name rotatory bladder, without knowing its functions. Some naturalists have taken those bladders for feet; but feet, entirely surrounded with a cuirass, and without any communication with the outside, would answer very ill the purpose of moving.

This spherical organ is always found under the orifice, and in the Closterium Lunula under the mouth (fig. 58. b.) and the intestinal tube. That bladder is transparent, round, circumscribed in itself (fig. 58. c. 62—63, a. 73. e. 65. c.), the number of which remains always almost the same. Diving downwards and upwards, they move in circular lines, as molecules do. In the Closterium Lunula, several are often found; in the Closterium costatum, never more than one; in the Closterium didymotocum we see two twin globules (fig. 65. e.), forming only one body, the union of which is still visible.

In a series of species of this genus, I have seen, globules without apparent bladder, moving freely towards the empty point of the valvules: which motion is distinctly seen in the Closterium acuminatum (fig. 59. e.). The vesicle surrounds the coat contiguous to the cuirass, and that coat cannot be separated from it but by galvanic strokes.

When the Closteria die, these animalcules retreat downwards, and present nothing more than a scarcely visible spot. In squeezing them under a flat and very thin bit of glass, I sometimes succeeded in obtaining them single, and then they appeared to me quite spherical, without the least mark of adhesion. In the Closterium Lunula and didymotocum, we discover under the rotatory bladder, and above the first, the marks of an intestinal tube in right line (e. e.), surrounded with the green substance, which fills the animalcules. In spite of the finest instruments and innumerable trials, I never succeeded in separating this tube, because the green substance, half liquid, mixed with large oily drops, cover the whole, and baffles every direct observation.

Speaking of the intestines, we must mention the coloured substance of these animalcules, which, surrounded with the coat, colours them in a particular manner. These substances appear to me in general gelatinous, half liquid, homogeneous, containing drops of oil or of fat, and very small solid grains.

In the Surirella Venus, this substance forms a brown or green mass (fig. 4. e.), heaped in the middle of the animalcule. In the Naviculae, the Frastuliae, and in some of the Diatomeae, this mass forms a small thin leaf, coloured, bent in its edges downwards, such as in the Frustulia appendiculata, (Pl. I. fig. 13. c. c.) which, when the animalcule dies, is irregularly dissolved. The genus Scalptrum and some species of non-described Naviculae, ean expell, without dying, the coloured content, through the opening found on the surface of the belly (Pl. V. fig. 70. b.) and these animalcules seem to possess the faculty of reproducing the content.

This content is equally seen in the Diatomeae and Fragilariae, and the two extremities of the body alone, being empty, are transparent. In the articulations of the Diatoma fenestratum, it merely consits in pale globules, always single and of various size (fig. 38.).

The genus Closterium, and those which are related to it, are on each side filled with a green substance, similar, though chemically different, to the chlorophylle of leaves: which substance covers large drops of a yellow oil (fig. 57. h. fig. 64. f.). This substance is here, as well as in the Frustuliae, intercepted in the middle of the body, and consequently divided into two equal parts. In the Closterium Lunula (fig. 57.), it is partly separated by sharp teeth; in other species, such as the Closterium spirale (fig. 67. h.), it appears like a green spiral ribbond in the cavity of the coat.

In the Pediastra, Euastra, Stauridia, Cosmaria and in the Colpopelta, the green substance fills entirely the two articulated parts of the animalcule, and hides often from one to four drops of oil (fig. 30. 31. 35. a. a.); but, near these drops, small solid and dark grains (b. b.) are seen swimming, and in a continual oscillatory motion, like the corpuscules of the rotatory vesicle of the Closteria. The same takes place in the Scenodesmi, Echinellae, Sphaerodesmi, etc.

In the Oscillatoriae the content consists in small disks, placed close one another, having only a small cavity, for ex. in the Oscillatoria labyrinthiformis (Pl. VI. fig. 76. a.).

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ORGANS OF PROPAGATION.

 

The organs of generation are in this series very obscure and problematic. I do not know them. I shall however hazard a few observations, perhaps of some importance, which may he brought under this head, as long at least as we shall not be able to point out these organs more positively.

The Naviculae and Frustuliae place themselves, two and two on the side of their pedal surface, and remain sometimes whole days in that position, and separate themselves again. I have seen a pair of the Frustulia agrestis (fig. 14. a.) united in this way, go slowly asunder, and remarked that, in spite of that apparent separation, both individuals were joined by two very narrow tubes (fig. 14. b. c.). And in magnifying them still more, I observed that these tubes passed through the cuirass and communicated with the brown content. I saw also upon the orifice of the tubes an areola forming itself by a thicker and darker content. They remained united about an hour, after which the separation took place as follows: The tube (c.) drew back in the animalcule (fig. 14. b.), and the tube (d.) towards (f.). Soon afterwards, having been able to observe the animalcule (f.) from downwards, or from the pedal surface, I saw (fig. 15.) in the middle line upon (d.) a larger opening, and upon (c.) a smaller one. In the last, the tube (fig. 14. b. d.) had drawn back; and the tube of the other animalcule entered into the first. In looking sidewise, I discovered, though rather indistinctly, both openings (d. c.).

Under the opening of the mouth, we find in the Pharyngoglossa, under the middle line and under the alimentary tube, a small round wart (fig. 16. d. and 16. b. d.), perforated in the middle, of a very doubtful function, and which, considering its position, I bring under this head.

In the Cosmaria, we find in each half of the animalcule (fig. 18. and 19.) a bladder in the axe (d.), and two other lateral ones (c. c.) of a darker colour, containing innumerable molecules, constantly turning and moving. I said above that the Cosmaria were to be considered as double animalcules, united during their whole life. In the Cosmarium deltoïdes (fig. 18—19.) I have seen both halves of the animalcule, separated during whole days, and two bladders, perfectly transparent and colourless, unloading in one another, and developing themselves. The bladders, where the contact took place, were visibly perforated. Soon after the developement of these bladders, I have seen the mass of the dark molecules of the bladder (d.) evacuated into the transparent one, in consequence of which a double stream of molecules (fig. 19. a. and b.) took place, crossing itself in the common opening, so that the molecules of the one ran into the bladder of the other animalcule, or part of it.

 

The Cosmarium bipes (fig. 20.) offers another instance of this exchange of a molecular fluid. We see here several animalcules under the form of a chain, united by obtuse points. Soon after this union, two other united animalcules open themselves by a long fissure (f.), and we see two streams of free molecules (fig. 20. a. g.) moving in the direction indicated by arrows, and operating in this manner the exchange of fluids.

The Closterium acuminatum presents an other instance of this exchange. In all the Closteria, seen sidewise, and where the two half cuirasses join, we discover two holes (fig. 57. 67. d. d. fig. 59. d. d. fig. 61. c.) opposite one another. The destination of these two openings was long for me a matter of doubt, till I could at last distinguish the junction of the Closterium acuminatum, in which two animalcules (fig. 59.) placed themselves obliquely one against the other, and till I saw, through these openings, the exchange of a transparent and scarcely perceptible fluid. In this union, we see also upon the cuirass an opening, both on the clear and on the convex side. This opening, however, is only visible during the union, described (fig. 59. x.). At all other times, in spite of all sorts of trials, I never could distinguish any thing.

The genus Echinella Ehrenb. (fig. 54—55.), beside the orifice (fig. 55. a.), has upon each cutting surface of its body, three lateral pores, consequently sex in all (fig. 54. 55. b. b. b.), passing through the cuirass. Though closely adhering together by these small cutting surfaces, I never could discover any exchange of fluids operated by these pores. The propagation of the Oscillatoriae and Diatomeae is probably performed by decomposition of the parts; I never saw, however, propagation take place by division, admitted and even described by several naturalists, such as it may be seen in Infusoria of a higher category, and such as it has been admirably described by Mr. Ehrenberg. What has been hitherto called division of individuals was only animalcules, parts of a whole or of a chain of animals. I never saw new limbs growing upon one of the animalcules separated from the chain; I never saw any one turning double, and consequently propagating itself either by a longitudinal or transversal division, nor after such a separation, artificially or violently executed, protracting its life, and still less, maintaining it, recuperating its individuality, and producing new animalcules of its own species.

The Oscillatoriae dissolve themselves in the already deceased lower parts, but a new animalcule never arises out of the fragments separated from that part. After having cut the filaments of the Oscillatoriae, I saw the one to which a part of the head was joined, creep, grow and continue to live, whilst the lower part, which had been cut, formed no new head, died, discoloured and discomposed itself.

In a series of observations, continued during several months, the Cosmarium stellinum alone presented an exception. After both animal bodies, half of which is represented (fig. 22. A.), are separated, a new sprout (fig. 22. B.) issues from the axe of each body. This sprout, at first round, exhibits later the first or principal incisions of its body, and afterwards those of the second and third rank. All the points and cuts are still obtuse and rounded; among the 52 points coming on each side of the body, 19 only are developed, which, divided later by new incisions, grow angulous, sharp and pointed. When the young animalcule has attained the size and form of the maternal part, the union continues still some time, and is soon separated, whilst the female animalcule advances towards death and dissolution, to repeat the above described process, and propagate in this manner its genus and species.

After having described the propagation of these animalcules, such as we have observed it, we shall venture to say a few words upon the question of aequivocal generation, which has been in our days a subject of so much controversy.

Reason speaks in its favour; I might almost say, acknowledges it, but the most direct and impartial observations seem to be in contradiction with it.

The water I put in contact with pure organic matter, with full certainty that no egg nor animalcule could have been mixed to them, and abandoned to putrefaction, has generated nothing, during 4—8 months, except polygastric Infusoria, some species of Monas and Colpoda, small Vorticellae, and very seldom a little Vibrio (Anguillula Ehrenb.).

The Naviculae, the Frustuliae, and in general the animalcules belonging to this series, object of the present observations, have never appeared but in cases where I could prove their external origin. I never found these animalcules (except the Oscillatoriae often generated in infusions) but in river or marsh waters, as well as all the more developed Infusoria and rotatory animals. Their propagation can be observed and obtained ad libitum in a room.

The equivocal generation has only reason in its favour and a very limited sphere of observations, owing to the excessive difficulty of observing such infinitely small creatures.

Propagation by sexual generation and by the formation of offsprings, has in its favour the greater mass of observations: which observations are positive in this case, and seconded by the form, appearance and size of these beings. The necessary conditions to these two modes of generation can be expressed by the following formule:

GENERATIO AEQUIVOCA.
SPONTANEOUS GENERATION.

ELEMENTS:	ACT:	PRODUCT:
− fluid substance, + solid substance, (− +) heat.	putrefaction, fermentation.	living being, heterogeneous to the substances employed to its generation.

GENERATIO SECUNDARIA.
SEXUAL GENERATION.

ELEMENTS:	ACT:	PRODUCT:
− male organ, + female organ, (− +) life.	receptivity and reception.	living being, homogeneous to those employed to its generation.

EXPLANATION OF THE PLATES.

PLATE I.

Fig. 01.	Surirella Venus, weakly magnified. Natural length of the cuirass: 0,002565. Breadth: 0,000104 of an inch (Paris).
Fig.„ 02.	Seen from above, more magnified.
Fig.„ 03.	Open animalcule.
Fig.„ 04.	Another, equally open; a. the cuirass; b. its inge; c. the white and transparent coat; d. incision, in the internal membrane; e. the brown or green content.
Fig.„ 04.	A. Ribs and furrows B. on the edge of the cuirass.
Fig.„ 05.	Navicula ciliata, two united animalcules. Length of the cuirass: 0,00044.
Fig.„ 06.	Separated animalcule, sidewise seen.
Fig.„ 07.	The same, seen from backwards; a. cuirass with angles and hairs; b. edge of the pedal surface; c. extremities of the sides; d. d. orifices of the alimentary tubes.
Fig.„ 08.	The same animalcule, seen from the pedal surface; e. d. d. orifices of the two alimentary tubes seen sidewise.
Fig.„ 09.	Navicula costata, seen sidewise; length: 0,00226.
Fig.„ 10.	The same, seen from downwards; a. cuirass; b. the brown content; b¹ b¹, pedal bladders; f. f. intestinal tubes, and their orifices; d. ombilic of the middle ribs.
Fig.„ 11.	Two united animalcules.
Fig.„ 12.	Frustulia appendiculata; two united animalcules. Length: 0,00139; breadth: 0,00055.
Fig. 13.	The same animalcule, seen from downwards; a. cuirass; b. pedal surface; c. c. brown content.
Fig.„ 14.	Frustulia agrestis; two united animalcules. Length of an animalcule: 0,00054.
Fig.„ 14.	b. The same e. f. standing and distant; c. d. the tubes uniting them.
Fig.„ 15.	An animalcule, seen from the pedal surface; c. d. the openings in which the tubes (fig. 14. c. d,) draw themselves back.
Fig.„ 15.	b. The same animalcule, seen sidewise; g. h. openings in the cuirass; e. d. openings of the tubes.
Fig.„ 16.	Pharyngoglossa sigmoidea; length of the animalcule: 0,002361. a. the stopple of the tube; b. the head; c. the foot of the anus; g. the anus; d. sexual warts. f. f. intestinal tube.
Fig.„ 16.	a. Head of the animalcule, seen sidewise, strongly magnified; a. the stopple; b. the fissures of the cuirass with the foot; f. the intestinal tube.
Fig.„ 16.	b. Head of the animalcule, seen from downwards; a. the stopple; b. the foot; d. sexual wart; i. brown content.
Fig.„ 16.	c. Posterior extremity of the animalcule; c. the foot; g. anus; f. intestinal tube; i. content.
Fig.„ 16.	D. Stopple a ², drawn from the opening a ¹ of the alimentary tube f., seen round the ligament b ¹, to which it adheres.
Fig.„ 17.	Frustulia viridescens, seen sidewise; a. a. pedal bladders. Length: 0,000185.

PLATE II.

Fig.„ 18.	Cosmarium deltoïdes. d. rotatory molecular bladders in the middle; c. c. the same bladders on both sides; e. point of junction of the two animalcules; f. warty cuirass. Size of the double animalcule: 0,000278.
Fig. 19.	The same animalcule, both halves separated; c. c. the lateral bladders; d. the middle ones with molecules; a. b. both bladders during the exchange of their molecular streams, in opposite direction.
Fig.„ 20.	Cosmarium bipes. Two double animalcules, united at their extremities; b. b. the pedal bladders; c. opening of the mouth; d. the middle molecular bladders; e. e. the lateral bladders; a. opening or fissure of the cuirass, by which is operated the exchange of the molecular streams. f. g. size of the double animalcule: 0,00212.
Fig.„ 21.	Cosmarium sinuosum. a. transparent edge of the cuirass; b. green content; c. middle rib; d. d. pedal bladders; e. opening of the mouth. Length of the double animalcule; 0,00075; breadth: 0,00031.
Fig.„ 22.	Cosmarium stellinum. A. Maternal animalcule. B. The offspring Each adult half of the animalcule is provided with 52 points on the cuirass. Size of the double animalcule: 0,009545.
Fig.„ 23.	Cosmarium truncatum, seen from the surface. Size of the double animalcule: from 0,003635 to 0,00400.
Fig.„ 24.	The same seen from the angle.
Fig.„ 25.	Cosmarium Pelta. c. brown content: d. the same already empty. Size 0,00043.
Fig.„ 26.	Cosmarium lagenarium. a. a. darker substances in the green content; c. cuirass with a shagreen surface; b. side, joining both animalcules. Length: 0,00894; breadth: 0,00328.
Fig.„ 27.	Cosmarium Cucumis. a. green content. Length 0,00221.
Fig.„ 28.	Colpopelta viridis. a. mouth and alimentary tube; b. shagreen-like cuirass; c. green content. Length: 0,00344.
Fig.„ 29.	Micrasterias falcata. a. oblique filament, joining both halves of the animalcule. Length of one part of the cuirass: 0,000165.

PLATE III.

Fig. 30.	Euastrum sexangulare. a. middle cell, with six corners; b. edge-cells in two parts; c. transparent middle-skin; d. oily drops of the green content. Size: 0,000345.
Fig.„ 31.	Euastrum hexagonum. Hexagon middle cells; d. transparent middle skin; a. thick oily drops. Size: 0,000915.
Fig.„ 32.	Euastrum pentangulare. a. Middle cell with five angles; b. cells of the octogone forked edges; c. transparent intermedial skin; d. green and solid content. Size: 0,003195.
Fig.„ 33.	Stauridium bicuspidatum. No middle-cell; a. intermedial transparent skin; green content, with small moveable oily drops. Size: 0,001765.
Fig.„ 34.	Stauridium Crux Melitensis. a. Middle skin. The largest diameter: 0,00785.
Fig.„ 35.	Pediastrum quadrangulum. d. Middle quadrangular cell, without intermedial skin, and consequently the intervals c. between the three empty and perforated cells; b. green content with molecules, and moveable oily drops. Size: 0,001765.
Fig.„ 36.	Pediastrum irregulare. b. irregular middle-cells; a. a. cells of the forked edges with a green molecular mass. Size: 0,000960.

PLATE IV.

Fig.„ 37.	Sphaerozosma elegans. Breadth of a member: 0,00095; a. globule uniting pairs of animalcules; b. b. these animalcules individually united by the intermedial membrane c.—d. d. oily drops with their content.
Fig.„ 38.	Diatoma fenestratum Ag. Length of a member: 0,00103; breadth: 0,00042. a. brown content in the cells of members d.—b. seen sidewise; c. common intestinal tube of a chain of animalcules.
Fig. 13.	Fragilaria undulata. Length: 0,00012; chain formed with three animalcules; a. a. two intestinal tubes; b. the foot; c. d. transversal tubes coming from each alimentary tube, so far as the edge c; e. cellular interval with a colored content.
Fig.„ 40.	The same animalcule, seen sidewise.
Fig.„ 41.	Diatoma Navicula. Length: 0,00104; breadth: 0,00025. a. orifices of a common alimentary tube; brown or green content of each cellular animalcule; b. a drop of oil.
Fig.„ 42.	The same animalcule, seen from the surface of reunion.
Fig.„ 43.	Desmidium didymum. Heigth of a member: 0,00055; breadth: 0,00199. Magnified chain of animalcules; a. intestinal tube; b. cuirass; c. flake uniting two animalcules.
Fig.„ 44.	Animalcule seen from the uniting surface; a. tube; b. cuirass.
Fig.„ 45.	Syrinx annulatum. Length: 0,00165; a. b. intestine tubes; c. cuirass; d. brown content; e. annular folds of the cuirass.
Fig.„ 46.	The same animalcule, seen from the uniting surface. a. h. intestinal tube.
Fig.„ 47.	Paradesmus foliolum, Chain of three animalcules; a. brown flake of the content; b. surface uniting two animalcules. Breadth of a member: 0,000255; length: 0,000540.
Fig.„ 48.	Scenedesmus ellipticus. 0,0040. Four united animalcules, not distant.
Fig.„ 49.	The same, distant; a. the animalcules; b. muscular flake of reunion.
Fig.„ 50.	Scenedesmus caudatus; a. b. three animalcules near one another; d. the fourth distant; c. flake of reunion; e. pedal hairs. Length of a member: 0,00047.
Fig.„ 51.	Meridion cordatum. Circular chain of animalcules; length of a member: 0,0095.
Fig.„ 52.	Separated animalcule; b. brown content.
Fig.„ 53.	Scenedesmus pyrus: 0,000355.
Fig. 54.	Echinella crenulata. Length without feet: 0,000115.
Fig.„ 55.	Two cells. a. mouth; b. b. lateral openings; c. c. square foot, common to both; d. d. brown content.

PLATE V.

Fig.„ 56.	Closterium Lunula Nitzsch; strongly magnified; breadth: 0,00316; length: 0,01735.
Fig.„ 57.	The same animalcule, still more magnified: a. mouth; b. rotatory bladder; c. intestinal tube; h. green content, with yellow oily drops; f. dented section; g. transversal band, transparent for want of the green content; d. d. the two lateral intermedial openings.
Fig.„ 58.	Point of a horn of the cuirass, strongly magnified; a. mouth; b. intestinal tube: c. rotatory bladder; d. dark corpuscules of this bladder.
Fig.„ 59.	Closterium acuminatum. Length: 0,00665. Perhaps the Closterium Leibleinii Kützing. (His drawing is too bad to ascertain it). Two united animalcules; a. the mouth; c. rotatory globules without bladder; e. intestinal tube and content; d. d. intermedial lateral holes; x. x. the same, by means of which both animalcules exchange their content; g. transveral bands.
Fig.„ 60.	The whole animalcule of the same species.
Fig.„ 61.	Closterium costatum. Thickness: 0,00147. A. A. Horns of the cuirass; b. b. mouth; a rotatory bladder; c. intermedial openings.
Fig.„ 62.	Edge of the cuirass valve, in the point of reunion of the two horns; d. its sides. 63. Point of the cuirass of the same animaleule; a. rotatory bladder; b. truncated extremity of the cuirass, as mouth; c. the rotatory globule in the bladder.
Fig. 64.	Closterium didymotocum. Length: 0,00928. a. mouth; b. rotatory bladder; e. twin globules of the bladder; e. intestinal tube; f. large oily drops surrounding the tube; h. green content; g. union of both parts of the cuirass.
Fig.„ 65.	Extremity of the cuirass, strongly magnified; a. mouth; d. rotatory bladder; e. twin globules; b. direction of their movement.
Fig.„ 66.	Closterium caudatum, strongly magnified.
Fig.„ 67.	Closterium spirale, strongly magnified; b. rotatory globule; d. middle opening; h. intestinal spiral tube (?)
Fig.„ 68.	Pleurosicyos myriopodus. Length: 0,000624. a. sides (8); b. pedal bladders; c. transparent and transversal band.
Fig.„ 69.	Animalcule seen from upwards.
Fig.„ 70.	Scalptrum striatum. Length: from 0,00085 to 0,00096; a. pedal bladders (?); b. middle opening, by which the brown content is emitted; longitudinal stripes between both sides c. of the cuirass.

PLATE VI.

Fig.„ 71.	Oscillatoria subulata. Thickness of the filament: from 0,00039 to 0,000465, strongly magnified; a. maternal filament; b. second filament; c. third filament; d. internodes; e. points.
Fig.„ 72.	The same; a. Maternal tube; the content forms a small head b., pushed forward for the object of creeping.
Fig.„ 73.	74. Oscillatoria elegans. a. the head, moving in the direction of the arrow, like a pendulum; b. tube of the filament; c. blue greenish content, thickness of the filament: 0,000145.
Fig.„ 75.	Oscillatoria amphibia. Strongly magnified; a. the head; b. division of a filament into two parts; thickness of it: 0,00046; heigth of the members: 0,00014.
Fig. 76.	Oscillatoria labyrinthiformis. Br.: 0,00081; c. tube; b. green content with a square cavity a; d. division of the content in the tube.
Fig.„ 77.	Oscillatoria Okenii. a. the head; b. the tube; c. the content; d. the cavity found within it; thickness of the filament: 0,000325.
Fig.„ 78.	Oscillatoria interrupta. a. the head; b. the sheath; c. the content of a gall-colour; thickness: from 0,000045 to 0,00006.
Fig.„ 79.	Oscillatoria laminosa. a. the head; b. the sheath; c. the content; d. empty interval; thickness of the filament: 0,000265.
Fig.„ 80.	Oscillatoria vivida. Thickness: from 0,00010 to 0,0008. a. content with small oily drops; tube.
Fig.„ 81.	Oscillatoria punctata. The green content, with black spots; lives amongst the precedent ones; thickness: 0,000015.
Fig.„ 82.	Melotomus Fragilaria. a. member of the cuirass; b. brown content; breadth of a member: 0,00033.
Fig.„ 83.	Ophiothria sphaerocephalus. a. surrounding the Oscillatoria interrupta; b. the head; c. the neck; thickness of the filament: 0,0017.
Fig.„ 84.	The same, more magnified; d. tube; d. green content.
Fig.„ 85.	Sphaerodesmus bicolor. Thickness of members: 0,000251; a. green globular members; b. orange-coloured internodes.
Fig.„ 86.	87. Sphaerodesmus depressus. Breadth of a member: 0,00018. a. transparent intermedial bladder; e. double members; b. transparent internodes.
Fig.„ 88.	88. Sphaerodesmus spirillum. Thickness: 0,000281. Fig. 89, natural thickness; fig. 88. rolled filament.
Fig.„ 90.	Middle cell a. and filamentous members b. of the same animalcule.