Abridgment of the Contemplation of Nature By Mr. Bonnet, of GENEVA

 

  1.  In the seventh chapter you have seen the earth worm regenerate; you have contemplated the progress of this regeneration; you have remarked a little bud that grew at the fore part of the stump, which unfolding itself by degrees, became a vermiform appendage, a kind of little worm, that seemed to be ingrafted on the stump.

This animal bud has discovered to you the first origin of the part that is reproduced. You have perceived that it was lodged in miniature under the fleshy parts of the stump, and that the latter does not contribute more towards this production than the earth does to the plants that have taken root in it.

Thus the earth worm contains, like the polypusses, a multitude of germs, which begin to unfold themselves as soon as certain accidents convey towards then the nutricious juices. The sources of reparation are here in proportion to the accidents that may threaten the animal. But the reproduction of the earth worm is much more astonishing than that of the polypus. It is not only an enormous Colossus in comparison of the polypus, but its structure is also much more compounded. It affords a more numerous apparatus of viscera, vessels, tracheze, muscles, &c. It has real blood, and this blood circulates. But it is besides an hermaphrodite: it unites at once all the organs peculiar to the two sexes. This insect, which in appearance is the most contemptible, would alone be sufficient to exhaust the sagacity of the ablest observer, though applying himself solely to the contemplation of it. What a gainer would physiology be from such an inquiry! What a number of truths, concerning which we should have no doubt, would then augment the treasures of our physical knowledge!

            2. The regeneration of fresh water worms presents us with the same phenomena as that of the earth worm, and their structure is likewise very much compounded. Several species of them are principally distinguished by their colour. All of them do not possess in the same degree the property of multiplying by slips. In general the polypus greatly, surpasses them in this respect; perhaps because its structure is more simple; and it may also be owing to its having a more ample provision of germs. Be that as it may, when we cut off the bead or tail, from the worms we are treating of, they do not tbemselves become worms; but all, or the greatest part of the intermediate pieces, how small soever they be, very easily regenerate themselves, and in a short time produce an equal number of complete worms.

Regeneration begins by a little pulling up of the anterior extremity: this puffing seems analagous to the vegetable roll. The wound closes and quickly consolidates. A little bud appears in the centre of the roll. This bud increases in size and length by degrees. New rings and new viscera begin to appear. You see from the rest what is to follow.

You also very easily comprehend after what manner each piece vegetates of itself. It has in miniature the same viscera as the whole exhibited at large. You have not forgot that the parts essential to life are here dispersed throughout the whole body, and that circulation is performed in the smallest pieces as in the whole worm.

Little buds or tubercles sometimes rise on the bodies of these worms, and give room to think that they are young ones growing from them, slips resembling those of the polypus, having the same origin and end.

This species of worm, from certain pieces of which a tail shoots forth in the part where a head should have been produced, affords a very singular phenomenon, which the frequency of it does not permit us to consider as the mere effect of chance. It also proceeds less from chance than the production of this supernumerary tail. It is too well organized not to have the same origin as that which shoots forth at the posterior extremity. But we cannot pretend to say what are the causes which here determine a tail to take the place of a head. We only know, that this kind of worm is very much exposed to the loss of its hind part; it is therefore, in all probability, furnished with more means for repairing this loss, than that of the fore part.

3. it would seem as if nature had proposed to herself a kind of diversion in the formation of insects. She has lavishly bestowed on them members and organs, which she has distributed but sparingly to other animals; to one she gives two hundred legs; to another twenty thousand eyes; to a third, several hundred lungs, &c. The production of new legs, new rings, a new head, and a new viscera, seem in these instances to be attended with no greater labour or difficulty than the productions of new hairs or new feather.

She often likewise disguises the same insect, and presents it to successively under such opposite forms, that they seem to many distinct beings. This leads to the metamorphosis of insects

4. We have had frequent occasion to acknowledge, that the proceedings of nature are not always uniform, and that she can accomplish the same end by very different ways. Look at this little, oblong black, smooth, and shining cone. It most resembles those cones which many insects construct to metamorphose themselves into. However, it differs from them in some essential particulars. View it through a microscope; you will then percieve in it some annular incisions, but not very deep, which discover to you its true nature, and at the same time informs you, that it is nothing but the skin of a worm, which is become round, and has contracted a hardness. Open it gently with the point of a needle, you find nothing in it but a kind of pap, in which you are able to discover nothing. The insect has but lately lost its form of a worm; how has it been reduced into that soft substance How will that become an insect Suspend your questions, and open a cone that is less recent than this. What do you discover in it A little mass of oblong, whitish flesh, in which you cannot perceive, even through a magnifying glass, the least signs of members or organs. In a word, you have before you an oblong ball. Do not imagine that this ball is a case that contains a nymph: it is itself a nymph that is much disguised. Press the ball a little: the legs begin now to show themselves: they come out of a little socket, that is at one of the extremities of the ball. Augment the pressure by degrees; you will force all the parts of the nymph to appear. They therefore exist already: but they were sunk and infolded within the ball, almost as the fingers of a glove might be in the hand of a glove.

If you could make the same experiment on the oviform bodies of net-polypuses, and on the buds of arm-polypuses, that you have lately made on the oblong ball, you would probably oblige the little polypus to produce itself, and by that means accelerate the time of its birth.

5. Insects that pass through the state of an oblong ball can therefore form themselves a cone of their own skin. All the parts of the nymph separate themselves by little and little from this skin. It grows round and hard about them; and under this singular arch they make an end of perfecting themselves. They are at first only of the consistence of a pap. This thickens by degrees. It assumes the form of an oblong ball; and when all the members of the nymph have acquired a certain consistence, they issue one after another from the inside of the ball, and arrange themselves like those of other nymphs.

By becoming a kind of cone, the skin of the insect does not lose in all the species, the form that was proper to the worm; some of them preserve it so well, that the metamorphosed worm scarcely differs at all from the worm that has not been yet transformed.

6. A hen that should, lay an egg as large as herself, from which a cock or a hen would be hatched, may offer to us such a prodigy, as we should find some difficulty in believing. A fly that is trouble. some to horses, and whose form has caused it to be named the spiderfly, affords us such a prodigy; and it should not seem the less strange, because it takes place only in an insect. Where there a law in the organical kingdom, to which we knew no exception, it would assuredly be that which ordained every organized body to grow after its birth. Nevertheless, here is a fly that lays a species of egg, from which is produced another fly as large and as perfect as the mother. This egg is almost round, white at first, and afterward of a black or ebony colour. The shell is firm and polished-but I must undeceive my reader: this is not a real egg, but has only the appearance of one; it is the insect itself that has assumed the form of an oblong ball in a cone made of its own skin. The thing is not the less wonderful on that account. All insects that metamorphose themselves, go through their various transformations, out of the belly of their mother. They are indeed to grow considerably before they undergo their first transformation, but do not grow at all afterward. We have an insect that transforms itself in the very belly of its mother, and acquires no farther growth after it has issued from it.

These cones of the spider-fly, these pretended eggs have been opened at different times; and in them have been found the same things that are discerned in the oblong ball-nymphs, when observed at their different ages. Moreover, there have been discerned stigmata in this species of cone that might be taken for a real egg, which is an evident proof that it was the skin of a worm that has transformed itself under this very skin. An egg is without motion: our cone has some that are very visible, and in certain circumstances the inside admits of their being seen, which attracts the attention of the observer. He seems to discern little clouds that succeed each other without interruption, and that pass with a progressive and uniform motion, from one end of the cone to the opposite one. In the cones that are laid before the time, these shadowy layers have a contrary direction from that which they have in the cones at the full time; You have seen that the circulation varies its course in the nymph; since our shadow layers change their’s likewise, they pretty clearly indicate to us, that the abortive cone is the worm itself, that has not yet gone through its metamorphosis. This worm, is in truth, a very singular being; it has neither head, mouth, nor any member: it is in appearance nourished like the eggs of birds, in the trunks that enclose them. A nice dissection demonstrates the ovary of the fly and the worm lodged in the middle.

7. When animals were divided into viviparous and oviparous, it was thought that all the species were comprehended. The fretter came first to clash with this famous division, and Convinced us that an animal was at the same time viviparous and oviparous. The arm-polypus next appeared, and presented us with an animal, that multiplying by slips, might with good reason be called ramparous There have even been observations made which seem to prove that it is likewise oviparous. Another species of polypus, that multiplies also by slips, and is extremely well characterized by a sort of plume, lays her eggs. These eggs may be preserved in a dry place for the space of whole months, like the seed of silk-worms ; and if after ward sown in water, there will be produced from them as many polypuses. The bulb-polypuses may be depicted by the epithet of bulbiparous. But bow shall we describe the multiplication of other cluster-polypuses, that of the net-polypuses, and of the millipes Lastly, the spider-fly presents us with another method of multiplying, in which there is nothing that is common with any of those above mentioned, and which is attempted to be expressed by the term of nymphiparous. How many other methods of propagating will there be discovered every day for which it will be necessary to create new terms!

8. One animal does not differ more from another than a worm from a nymph. And what renders this metamorphosis still more surprising, is, that it seems to be performed instantaneously.

What then is the procedure of nature in this respect She ia other instances advances by degrees. An insensible developement brings all organized bodies to a state of perfection. Can this law, which is so universal, suffer any exception A fact which I am going to relate, will help us to penetrate this mystery.

Let us confine ourselves to caterpillars; they are sufficiently known to us, since the silk-worm is a real caterpillar. The caterpillar from time to time changes his skin, and that is common to him and most other insects. These moultings are termed maladies in the silk-worm, and they are so in effect. But it is very material to observe, that the skin which the caterpillar casts off at each moulting, is so complete, that it seems to be of itself a real caterpillar. There are found in it a head, eyes, a mouth, jaws, legs armed with hooks, stigmata, and generally all the external parts proper to the insect.

How is the caterpillar enabled to divest itself of so many organs, and clothe itself with new ones resembling the first Nothing can be more simple than this: new organs were lodged in the old ones, as in so many cases or sheaths. In changing its skin, the caterpillar had occasion only to draw them away, and drew them away accordignly. because the cases proved too strait.

This jointing is so real, that it may be perceived by the naked eye. it may even be demonstrated by a very easy experiment. If, on the approach of the moulting, we cut off the former legs of the caterpillar she will issue from her spoils without any legs at all. Thus this caterpillar, which we considered as a simple and singular being, was  some measure, a multiplied being, or composed of several similar beings joined into each other, and that successively unfold themselves.

9. Hence arises a very probable conjecture: may not the chrysalis be lodged under the last skin the caterpillar is to cast off May not this skin be a mask that conceals it from our sight

A celebrated observer has, by a decisive experiment, assured himself of the truth of this conjecture. He has removed the mask, and has by this means discovered the chrysalis in a manner very easy to be distinguished. He has seen the six legs of this chrysalis to grow out of the six former legs of the caterpillar, and all the other members of the latter to be wrapped together under different parts of the former.

The metamorphosis of insects, then, enter anew into the order of developements and confirm it. The chrysalis, or rather the butterfly, for it is in the strictest sense but a swaddling butterfly; the chrysalis, I say, pre-existed in the caterpillar, it does no more than unfold itself in it, and the caterpillar is a kind of machine prepared for performing afar off this developement. It is in some respects, to the chrysalis, what the egg is to the chick.

10. In truth an insect that must moult five times before it is invested with the form of a chrysalis, is a compound of five organized bodies, enclosed within each other; and nourished by common viscera, placed in the centre.

As the bud of a tree is to the invisible buds it encloses, so is the exterior part of the caterpillar newly hatched to the interior bodies it conceals in its bosom. Four of these bodies have the same essential structure, and this structure is that which is peculiar to the insect in the state of a caterpillar. The fifth body, which is very different, is that of the chrysalis. The respective states of these bodies are in proportion to their distance from the centre of the animal. Those that are the farthest off have more consistence, or unfold themselves soonest.

When the exterior body has attained its full growth, the interior, which immediately follows, is considerably unfolded. It soon finds itself lodged in too narrow a compass. It stretches on all sides the sheaths that encompass it. The vessels which convey the nourishment to these coverings, being broken or stifled by this violent distention, cease to act. The skin wrinkles and dries up. At length it opens. and the insect appears clothed with a new skin and new organs.

A fast of a day or two precedes each moulting. It is probably occasioned by the violent state in which all the organs then are.  Perhaps it might be also necessary in order to promote the success of operation, and prevent obstructions. Be this as it may, the insect weak after every moulting. All its organs are yet affected by state they were in under the covering they are just disengaged from The scaly parts, as the head and legs, are almost entirely nous, and are all imbued with a liquor that insinuates itself betwixt the two skins, and facilitates their separation. But this moisture evaporates by degrees: all the parts acquire a consistence, and the insect is in a condition to act. The first use that some species caterpillars, which live only on leaves, make of their new teeth, it to devour greedily their spoils: sometimes they will not even wait for doing it, till their jaws have received their full degree of strength Can these spoils be a proper ailment to renew and increase their strength Some caterpillars have likewise been seen to gnaw the shells of their eggs after they have issued from them, and even that of the eggs of such caterpillars as have not been hatched.

11. When we have once conceived that all the exterior parts of the same kind are jointed into each other, or laid one on another, the production of new organs has nothing embarrassing in it; and with regard to this, there is not any essential difference betwixt the five moultings that precede the transformation. Nothing more is requisite in all that, but a simple developement.

But it is not absolutely the same with respect to changes that happen in the viscera before, during, and after the metamorphosis. Here the light that should guide us is almost extinguished, and we are constrained to grope in the dark.

It does not appear that the insect changes its viscera as it does its skin. Those which existed in the caterpillar, exist likewise in the chrysalis; but they are modified, and it is the nature of these modifications, and the manner by which they are performed, which elude our researches.

A little before the metamorphosis, the caterpillar rejects the membrane that lines the inside of the intretinal bag. This bowel which has hitherto digested gross food, must hereafter digest that which is extremely delicate. The blood that circulates in the caterpillar, from the hind part towards the head, circulates a contrary way after transformation. If this inversion be as real as observations indicate, what idea does it not give us of the changes the inside of the animal experiences Those which the circulation of the blood in a new born infant undergoes, are in a manner nothing in comparison of them.

12. Whilst nature is labouring to change the viscera, and to give them a new life, she is employed at the same time in the developement of divers organs, which were useless to the insect while it lived under the form of a caterpillar, and which the new state. whereunto it is called renders necessary for it. The better to ensure the success of her. different operations, she causes the insect to fall into a deep sleep, during which she carries on her work at leisure and by insensible degrees.

The little wounds which the rupture of several vessels has occasioned in divers parts of the inside, consolidate insensibly. Those parts which had been put into a violent exercise, or whose forms and proportions had been modified to a certain degree, conform themselves gradually to these changes. The liquors which are obliged to pass through new channels, take that direction by little and little, Lastly, the vessels which were proper to the caterpillar, some of which occupied a considerable place within it are effaced or converted into a liquid sediment, which the butterfly rejects after having laid aside the sheath of the chrysalis.

13. When we consider the metamorphosis of insects, we are surprised at the singularity of the means which the Author of nature has thought proper to make choice of, in order to bring the different species of animals to perfection.

Wherefore is the butterfly not bred a butterfly Why does it, pass through the state of a caterpillar, and that of a chrysalis Why do not all the insects that metamorphose themselves undergo the same change Whence does it happen, that amongst the species that assume the form of a nymph some shed the skin of a worm, whilst others retain it How does it also come to pass that among such insects as pass through the state of the worm skin nymph, some take that form in the very belly of their mother

These questions, like all those which may be started concerning essences, derive their solution from the general system which is unknown to us.

Without endeavouring then to penetrate into the cause of metamorphosis, let us observe attentively the fact, and its immediate consequences.

Let us consider the variety which those metamorphosis disperse throughout nature. A single individual unites within itself two or three different species. The same insect successively inhabits two or three worlds ; and how great is the diversity of its operations in these various abodes!

Let us also remark to what degree the relations which the fly or the butterfly maintains with the beings that surround them, are multiplied by their metamorphosis. Let us fix our attention on the cone of the silk-worm; and admire what a number of hands and machines this little ball sets to work. What prodigious riches should we have been deprived of, had the butterfly of the silk-worm been originally produced in that form

Insects that undergo transformations have not yet afforded us and species that multiplies by slips and shoots. This will not surprise us, when we reflect on the great composition of the bodies of these insects. But let us not be too hasty in our judgment, nor conclude that the property of multiplying by slips arid shoots is incompatible. with metamorphosis. Nature is too little known to us, to give us a right to form such conclusions. Vine-fretters and polypuses have furnished us with good preservatives against too general conclusions.

Chapter 10 - Parallel Between Plants and Animals