would be fo great, in animals of fuch extreme minuteness, as to make them appear animals of two different fpecies? And, if they really are animals of two different fpecies at firft, how can they afterwards become animals of the fame fpecies, differing only in fex? My third obfervation refpects the origin of those small animals. They are not found, according to Leewenhoek, and those who adopt his fyftem, in early youth; at the age of puberty, their number is prodigious; they almost all perifh in difcafe; they appear again, on the return of health, and the vaft quantity,loft at the union of the fexes, is always fupplied while the generative faculty remains. From all thefe facts, we cannot but conclude, that thefe animalcules are generated in the body which harbours them; and, if they are there generated, I demand how this takes place. Are they formed there, by an immediate production, or by way of propagation? If they are formed by an immediate production,, we muft allow, the there refides in the feminal matter, or in the veffels which form it, a faculty, capable of producing daily, hundreds of millions of living beings, without the afliftance of any animalcule;, and if fo, why may it not be allowed, that the fœtus can be produced in the fame manner, without the fame affiftance, by a fimilar faculty? But, if it is maintained, that the animalcules in queftion are multiplied in the fpermatic fluid, by the way of propagation, they must not only be fit for generation, long before attaining the age of maturity, and in a state, in which they could hardly be faid to have begun to be animals; but, according to the principles of Leewenhoek, we must also allow, that in their femen, there are other animals, infinitely fmaller, to which they owe their origin, as thefe other animals muft, in their turn,owe theirs to animalcules, fmaller ftill, in the fame proportion, which might be carried ad infinitum, unlefs we fhould find at laft fome, whofe femen had the faculty of fecundating the female, without the affiftance of fmall animated pre-existing beings. And, if we must come to that at laft, what do we gain by the system of Leewenhoek? And, why not allow the fame faculty to the femen of larger animals? In the fourth place, if it is maintained, that the fœtus is formed of one of thefe fmall fpermatic animalcules, we muft fuppofe it to grow, with fuch furprising rapidity, as, if it is not altogether impoflible, is at leaft incredible, and has no no example, that I know of, among other animals. Let us fuppofe, that, in ten days after conception, the fœtus of a bitch has only attained the fize of a pea: that a pea is equal to five hundred grains of fand, and that a grain of fand is a million of times larger than the feminal animal of the dog, as Leewenhoek himself affirms, in his letter of the 13th July, 1685, Edit. 1696; we fhall find, by calculating on thefe data, that this foetus has become, in ten days, five hundred millions of times larger than it was. Such an aftonishing growth will appear the more fingular, that there is here no unformed mafs of matter, increafing by an external accretion of parts; but, that it is, according to the fame author, an organized body, with a stomach, intestines, and other parts, which enter into the conformation of our body, and each of which, like it, grows by intus fufception. But, if the fpermatic animals grow with fuch celerity in the uterus, is it not, in the fifth place, very strange, that they should not grow in the femen, although they are there immerfed in their native fubftance, which nourishes them, and preserves their life? By what miracle does it happen, that an animal, which, in the uterus, can become, in ten days, five hundred millions of times larger than it was, cannot grow in the femen, however long it may remain there. Does not a circumftance, fo incomprehenfible, lead one to believe, that the animalcule and the foetus, are beings of a very different kind, and that the one, by no means proceeds from the other? In the fixth place, it appears ftrange, that of fo many hundred millions of animalcules, which, it is faid, enter at one time into the matrix of the larger terrestrial animals, there thould be only one or two, or at moft feven or eight, according to the fpecies which become foetufes there. If the fœtus proceeded from the fpermatic worm, we should naturally expect to find in the matrix, some days after copulation, a vast number of foetufes. But we find no fuch thing. All that are found, are merely the small number of fuch as are deftined to become perfect animals. According to the idea of Leewenhoek, who denies the existence of an ovarium, we cannot account for an event fo little agreeable to nature, except, in fuppofing, that among thofe myriads of animalcules, there are only a few that have received the faculty of exifting, or, that in the uterus, there are but few places proper for receiving and fostering thofe little beings: we muft muft likewife fuppofe, that thefe places are exceedingly fmall, otherwife we must believe, that a fingle place would be fufficient for a great number, at least for a certain time. Thofe who imagine, that the foetus of all animals, proceeds from an egg, are likewife at a lofs to extricate themselves from this difficulty. Some take it for granted, that after the egg is detached, as they pretend, from the ovarium, and has fallen into the matrix, there is a very narrow aperture in it, at the place by which it adhered to the ovarium; that this aperture is fhut by a valve, which permits the entrance of the fpermatic worms that thefe worms, by a natural inftinct, endeavour to enter by the aperture; that, when one has got in, its tail preffes upon the valve, and fhuts the entrance against the reft, and, that this is the reafon, why there is only a fingle foetus in each egg, and that fuch a multitude of animalcula produce fo few fœtufes. But all this requires another fuppofition, contrary to experience, namely, that the egg, which, they fay, has fallen into the matrix, muft be fo fmall, that a worm, a million of times less than a grain of fand, cannot extend itself in it, its whole length; for, without fuppofing this, its tail could not prefs against the valve, and keep it fhut. Now, it is very certain, that these bodies, which are taken for the eggs of the ovarium, are of a very difcernible bulk, and infinitely exceed that of the animalcula in queftion. Others pretend, that the femen rifes in vapour in the matrix, and that this vapour, being loaded with animalcules, penetrates to the ovarium, through the Fallopean tube: that at this time, the pores of the eggs ready for fecundation, are so open, that they permit the entrance of the animalcules; that one accordingly does enter, keeps itfelf there, and grows; that afterwards, the egg, become thereby heavier, detaches itself by its own weight from the ovary, and falls down into the matrix. But, muft not this explanation appear exceedingly forced, when we reflect, that before it can be admitted, we muft fuppofe, contrary to all probability, that although all the pores of the egg are open, there enters but a fingle animalcule; or that, if many enter, only one of them grows there? There is fomething very fingular in all this; and an opinion, deftitute of proofs, and which, in order to be supported, must have recourfe to vague and forced fuppofitions, is not likely to gain ground. Z z Let Let us reflect further in the feventh place, on the conduct which this opinion obliges us to afcribe to the Creator. It prefuppofes that this omnifcient being, in order to produce a fingle perfect animal, has been obliged to form fo many hundred thoufand imperfect beings that the number is inconceivable. Does fuch a conduct correfpond to that which we fee reign in the other operations of nature, where all things tend to their ultimate perfection by the most direct, the fimpleft and shortest course? I know that the ways of God are not as our ways; that it would be culpable temerity to condemn his works because they are not conformable to our ideas, and that tho' we do not comprehend the reasons which may have induced the fupreme Being to act in fuch a particular manner, we ought not to be the lefs convinced that these reasons have been conformable to his infinite wisdom. If therefore it were demonstrated, that generation takes place in the manner which Leewenhoeck and his followers pretend, far from impugning, I thould confider it as the strongest proof poffible that the thing was fo. But I know likewise on the other hand, that when on the ftrength of our own weak reason, we would attempt to account for the operations of nature, the refpect we owe the Creator fhould render us careful not to attribute to him a conduct which we can fuppofe unfuitable to the ideas we have of his adorable wifdom; and in this view I think the fyftem in queftion faulty. It will perhaps be objected to me, that what I here condemn as a fault in the Syftem of Leewenhoeck we have nevertheless very frequent examples of in plants, which produce incomparably more feeds than are neceffary for the prefervation of their fpecies, and of which a great part perishes without having contributed to this purpose. But if we bestow a little attention we fhall find that this example has no relation to the prefent cafe. For befides that there is no proportion between the number of fpermatic worms which are produced in a fingle animal, and that of the feeds produced by the moft fertile plants, the feeds of vegetables are not defined merely for the prefervation of the fpecies, they are likewife deftined for the nourishment of animals. They make the principal part of the food of man, and of the greater part of the food of birds; this is a fact we know, but we do not fee how the prodigious number of animalcules, which རྩ་གན་ན། perish perifh in the uterus; can be of the fame ufe there. Add to To all thefe difficulties which regard animals in general,there are others which respect man in particular. It is allowed that the animalcules, of which it is pretended man is formed, are living, animated beings. I afk what is the nature of the foul which animates them? Is it the foul of a brute? Is it a foul endowed with reafon? If it be the foul of a brute, then is man compofed of three distinct principles, a body, the foul of a brute, and a foul endowed with reafon: This is what I fuppofe the advocates for the fyftem of Leeuwenhoeck will not admit, and which would indeed be an opinion too fingular to be admitted without proof or foundation. But if it is a rational foul, and the fame which animates our bodies, as Leeuwenhoeck makes no difficulty in averring, can we conceive, that in order to form our body, the least noble part of us, God created fo many myriads of rational fouls, all except one or two destined to destruction? Would that accord with the notions we entertain of his infi. nite wifdom? I fhall be told perhaps, that while these fouls refide in the animalcules, they have not yet acquired rea fon, and that they do not acquire it but by degrees from the knowledge the man receives as he grows up; at least it is thus that a difciple of Wolfius would reason. But this would not remove all the difficulty. The foul of the animalcule would always be effentially the fame with that of man; it would always be a foul capable of receiving the perception of objects as they fhould be prefented to it, and of reflecting on thofe objects. All the difference would be, that in the body of the animalcule thofe objects would be prefented to it fewer in number and more obfcurely; but this defect, which proceeds from the condition and imperfection of the body 1 |