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tti. It is thus that, proceeding on supposition, it is easy to account for every phenomenon, even for the existence of things which have never existed, as those philosophers have done, who have explained to us the way in which putrefaction engenders insects. I have perhaps at present imitated them, by founding, in the instance of the -J ama folium, on facts, which, though pretty generally received are not on that accoxint the more worthy of credit. I kndw at leaft that Vailisneri, has endeavoured to render them doubtful, and to maintain that theTænia is nothing but a chain of worms called Vtrmes Cucurbit mi, which are linked to one another, and thus form aggregately the figure of a -single animal. The seasons he alledges have agooddeal of plausibility, and seemfo strong that at, present a person would be accused of prejudice not to subscribe to his opinion. But I must own they have not entirely convinced me. The difficulties which have occurred to me on the subject, will induce me to neglect no opportunity of Endeavouring to discover the truth j and till I have examined the animal alive, which I shall do if I can procure it, I know not whether I shall adopt the opinion of that learned author, or continue of the contrary side.
What has been said sufficiently sliews that though it i* probable that there may be insects which multiply naturally without the common process by which generation is accomplished, the fact is not yet demonstrated. But what may be advanced as a certain fact, though it has stiil more the appearance of a paradox is, that there are animals which cart be made to multiply, and which in fact do multiply by art, without the common generative process, as we ihall have occasion to shew in the sequel.
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Engendered by nil forts of matter. Aristot. Hist. Anim. L. j.c. 19, Procreantur porro insecta, aut ex animalibus generis cjusdem - - - aut non ex animalibus, fed sponte; alia
ex rore qui frondibus insudat; item alia ex cæno et fimo
putrescente oriuntur: alia in lignis aut ftirpium, aut escsis: alia in animalium pilis, aha in txcrementis, aut jam excretis aut adhuc intra animal contentis. Add. Plin. Hist. Nat. h. II, cap. 33.
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The covered rrfscl did not nntr.in any animals. To the cx
experiments periments of Rhedi, may be opposed that made by Leewert-" hoek, which he relates in his letter of the 14th of Julv, 1680. He there fays, that he had heard various opinions on the generation of insects: that he had even learnt, that a certain author had maintained, that, if a vessel, containing water and flesh, were carefully shut, no animal could be produced in it: that this had led him to try the experiment; that, having taken for this purpose, two tubes of glass, shut at the bottom, he had filled them half full of pepper, and had poured on water, so as to fill the glasses about threefourths. It was rain water, recently fallen, and was received into a porcelaine jar, very clean, and which had not been made use of for ten years: that having hermetically sealed the top of ane of these glasses, and having left only a small opening in the other, he examined the water three days afterwards in the open tube, and discovered in it, a great number of very minute animalcules of different kinds, moving in all directions: that having, on the fifth day, broken off the end of the sealed tube, the air issued with violence, and he discovered in the water of this tube, a species of globular animals, larger than the largest of those in the other tube. Here, then, were animals generated, in a place closely shut, and where no insects could enter to deposite their eggs: which appears quite contrary to the experiments of Rhcdi, and furnishes an argument in favour of equivocal generation. But, if we, attend to the animals which make the subject of these experiments, the difficulty will soon he removed. It is certain, that the experiments of Rhcdi were made on those maggots that are of a seniible bulk, and which, without the aid of a magnifier, are every day seen in putrid animal substances. His object was to prove, contrary 'o the opinion of the antients, that these maggots were not produced by the corruption of the animal matter, but sprung from eggs which flics had laid in it; and this appeared clearly from the precautions he took to keep off the Hies. He conrcr.ted himself, with covering the mouth of the vessel with a thin clo h, a precaution which would have been useless agiinit infects, incomparably more minute, but which was sufficient to exclude common flies.'
The expeiiincnt of I.eewcnhock, on the contrary, respt els ahirns's of a quite dtffcrcr.t kirn!, animals, of which a vast number may livein it luiul! quantity of water: animals which he
calis <afls very minute, that is, in his ordinary stile, animals, that k would require a million of, nay ten millions, and some- •* times an hundred millions, to compose the bulk of a grain pf sand; in a word, animals which one would not suppose a microscope could make visible, had he not taken care to demonstrate its possibility. We easily fee, that the precautions which Leewenhoek took, to exclude such animals from the tube he had sealed, were by no means sufficient. These animalsor their eggs, might have been, either among the pepper,or in the rain water he employed,or even in the air which filled the void in his tube: there was, therefore, nothing surprising, in animals being found there, five days afterwards. To overturn, by his experiment, what bad been proved by Redi's, Leuwenhoek ought, at least to have boiled the water and the pepper in the very tube, and then to have sealed it immediately. If he hud then found, some days afterwards, any animals in that water, his exp.'rimcnt would very much have disconcerted the modern naturalists 1 but, I am persuaded, that is what would not have happened.
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From which similar insefls are to be generated. This ingenious comparison, which sliews the conformity of infects with plants, is similar to that made by Swammerdam, in the first part of his General History, where he compares the de» velopement of the different orders of insects with trie plant called the carnation. The greater animals may, in some respects, be likewise brought into the comparison of M Lesser, since all, or at least, many of them, proceed likewise from an egg; that all of them increase, by means of a nutritive fluid j and that in general, they do not propagatŒ their kind, till they have attained their ultimate perfection. It must, however, be confessed, that some of the analogies which our author discovers between insects and plants, are but imperfect. That, for instance, of the wings of insects with the leaves, seems a little far fetched; for, in the first place, the leaves appear, almost as soon as the bud begins to ©pen, while she wings of insects never make their appearance, tid they have attained their perfect state. Secondly, The leaves grow slowly after being disengaged from their gems } but the wings of infects, after having quitted their covers, elongate themselves immediately, and acquire their full size in a few minutes. Thirdly, the number of leaves in a plant is not fixed j they fall and arc renewed, and this
P p vicisstfud* vicissitude lasts as long as the plant itself: but the number of wings in every different insect is invariable, and a wing once lost, can never be supplied. Lastly, according to the conjectures of the most able botanists, the leaves are given to plants, to desend the root.and the stem from the heat of the Sun.to facilitate the evaporation of superfluous humidity, and to promote the circulation of the sap, which is to elaborate and prepare the shoots, the fruit and the seeds; while the wings are bestowed on insects, for a very different purpose, to wit, to facilitate their motion from place to place. Be. sides, if the wings of insects in general, resembled what ij said of those of a certain Indian insect, called in that coun try, the "walkiog leaf, (Cicada foliacea; Gryllus siccifoliut,) their analogy with the leaves of plants, or at least of trees, would be more remarkable. The wings of these insects, not only in the form and nerves of the wings, resemble the leaves of trees, but in their colour. I have seen some of them with wings of a bright green, others, with wings of a darker green, and like that os a leaf at sull growth, and others of the colour os a withered leaf. It is said, that their wings are of the sirst crlour in spring, of the second in summer, and of the last in autumn; that afterwards, they fell, and that the insct remains withom wings during the - winter, and that they shoot forth again in the spring. If all these circumstances were true, we could not deny, but that the wings of this hisrct had a very marked analogy with the leaves of trees; but, at the fame time, we must allow, that in this respect, it differs from other insects, and is probably unique in its kind; at least, there is not, so far as I know, any other, whose wings are liable to the fame viciflitude.
In sine, it may be observed, that the comparison made by the author, between a nymph or chrysalis, from which a persect animal issues, and a flower-bud, which produces fruit in its maturity, exceeds somewhat, the terms of the. parallel in question. His object was to shew the analogy between insects and plants. For this purpose, the author compares the egg of an insect to the seed of a plant, its body to the stem, and its wings to the leaves. It would be necessary, in order to compleat the analogy, to compare some Other part of the insect with the flower-bud, but not to compare with it, tne entire insect, as he has here done.
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this place, with instancing only one mark of consormity between insects and other animals, it was not for want of more: but, because the one mentioned in the text, is that which distinguilhes them most remarkably from vegetables: in general. The analogies, however, which subsist between insects and other animals, are very numerous, and in order to mention some of them, I shall observe, sirst, that both of them grow, and are propagated, almost entirely in the same way. S. That the internal parts of the one, are analogous to those of the others. All insects, like the larger animals, with sew exceptions if any, have a stomach, intestines, a heart, Veins, lungs; a brain, spinal marrow, muscles, an ovary, &c. 3. That insects likewise are endowed with senses. All have taste and seeling, the greater part have sight, and probably also smell, nor can it be doubted, that many have hearing. [*The ears of insects have been lately demonstrated by Prosessor Fabricius, who published an account; with sigures of those organs, in the crab and lobster, in the New Copenhagen Transactions, Vol. II. p. 375. That eminent fcntomoldgist found the external orisice of the organ in these animals, to be placed between the long and the short antenna:, the cochlea, &c. being lodged in the upper part of what Linnæus calls the thorax, near the base of the serrated projection at its apex. As these animals, therefore, are true inftcts, it is reasonable to conclude, that the rest of the claft are likewise provided with similar organs, in the fame places.] 4. That they appear also, to be endowed with the, paflions; especially with that of love, scar and anger. 5. That they exhibit traces of memory, and a certain degree of intelli* gence. 6. That each has its peculiar industry, artisice; manner of attack, desence, and method of attending to its! town preservation. 7. That a diversey of characters is observable among them. Some are bold, timid, active, slothsul, patient, headlong, Orong, weak, social, solitary, neat, sluttish, temperate, voracious. In a word, hardly any thing is to be seen in the organs, dispositions, manner of living, and acting in the larger animals, of which we may not sind traces in insects; so that it cannot be denied; but that their analogies with these animals, are incomparably more real, and more distinct, than those with plants.
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Approach to the natur: of vegetables. Although among inF p % sects*