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. would be so great, in animals of such extreme minuteness, as to make them appear animals of two different species? And, if they really are animals of two different species at first, how can they afterwards become animals of the fame species, differing only in sex?

My third observation respects the origin of those small animals. They are not found, according to Leewenhoek, and those who adopt his system, in early youth; at the age pf puberty, their number is prodigious; they almost all perish in disease; they appear again, cn the return of health, and the vast quantity,lost at the union of the sexes,is always supplied while the generative faculty remains. From all these facts, we cannot but conclude, that these 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 must allow, t'.^i there resides in the seminal matter, or in the vessels which form it, a faculty, capable of producing daily, hundreds of millions of living beings, without the assistance of any animalcule -, and if so, why may it not be allowed, that the sœtus can be produced in the fame manner, without the (ame assistance, by a similar faculty? But, if it is maintained, that the animalcules in question are multiplied in the spermatic 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 said to have begun to be animals; but, according to the principles of Leewenhoek, we must also allow, that in their semen, there are other animals, infinitely smaller, to which they owe. their origin, as these other animals must, in their turn,owe theirs to animalcules, smaller still, in the same proportion, which might be carried cd hifinitum, unless we should find at last some, whose semen had the faculty of fecundating the female, without the assistance of small animated pre-exitting beings. And, if we must cOme to that at last, what do we gain by the system of Leewenhoek? And, whynot allow the same: faculty to the semen of larger animals?

In the fourth place, if it is maintained, that the foetus is formed of one of these small spermatic animalcules, we must suppose it to grow, with such surprising rapidity, as, if \t is not altogether impossible, is at least incredible, and has

«9 no example, that I know of, among other animals. Let us suppose, that, in ten days after conception, the fœtus of a hitch has only attained the size of a pea: that a pea is equal to five hundred grains of sand, and that a grain of sand is a million of times larger than the seminal animal of the dog, as Leewenhoek himself affirms, in his letter of the 13th July, 1685, Edit. 1696; we shall find, by calculating on these data, that this fœtus has become, in ten days, five hundred millions of times larger than it was. Such an astonishing growth will appear the more singular, that there is here no unformed mass of matter, increasing 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 fufeeption.

But, if the spermatic animals grow with such celerity in the uterus, is it not, in the fifth place, very strange, that they fliou'.d not grow in the semen, although they are there immersed in their native substance, 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 semen, however long it may remain there. Does not a circumstance, so incomprehensible, 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 sixth place, it appears strange, that of so many hundred millions of animalcules, which, it is said, enter at one time into the matrix of the larger terrestrial animals, there should be only one or t\vo, or at most seven or eight, according to the species which become foetuses there. If the fœtus proceeded from the spermatic worm, we should naturally expect to find in the matrix, some days after copulation, a vast number of foetuses. But we find no such thing. AU that are found, are merely the small number of* such as are destined to become perfect animals. According to the idea of Leewenhoek, who denies the existence of an ovarium, we cannot account for an event so little agreeable to nature, except, in supposing, that among those myriads of animalcules, there are only a few that have received the faculty of existing, or, that in the uterus, there are but few places proper for receiving and fostering those little beings: we must likewise suppose, that these places are exceedingly small, otherwise we must believe, that a single place would be sufficient for a great number, at least for a certain time. Those who" imagine, that the fœtus of all animals proceeds from an egg, are likewise at a loss 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 (hut by a valve, which permits the entrance of the spermatic worms: that these worms, by a natural instinct, endeavour to enter by the aperture; that, when one has got in, its tail presses upon the valve, and shuts the entrance against the rest, and, that this is the reason, why there is only a single fœtus in each ej>g, and that such a multitude of animalcula produce so few foetuses. But all this requires another supposition, contrary to experience, namely, that the egg, which, they say, has fallen into the matrix, must be so small, that a worm, a million of times less than a grain of sand, cannot extend itself in it, its whole length; for, without supposing this, its tail could not press against the valve, and keep it shut. Now, it is very certain, that these bodies, which are taken for the eggs of the ovarium, are of a very discernible bulk, and infinitely exceed that of the animaleula in question. Others pretend, that the semen rises in vapour in the matrix, and that this vapour, being loaded with animalculrs, 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 itself 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, must not this explanation appear exceedingly forced, when we reflect, that before it can be admitted, we must suppose, contrary to ail probability, that although all the pores of the egg are open, there enters but a single animalcule; or that, if many enter, oaly one of them grows there? '• ,

There is something very singular in nil this; and an opinion, destitute of proofs, and which, in order to be supported, must have recourse to vague and forced suppositions, is act likely to gain ground.

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Let us reflect further in the seventh place, nn the conduct which this opinion obliges us to ascribe to the Creator. It presupposes that this omniscient being, in order to produce a single perfect animal, has been obliged to form so many hundred thousand imperfect beings that the number is inconceivable. Does such a conduct correspond to that which we see reign in the other operations of nature, where al) things tend to their ultimate perfection by the most direct, the simplest and shortest course?

11 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 supreme Being to act in such a particular manner, we ought not to be the less 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 should consider it as the strongest proof possible that the thing was so. But I know likewise on the other hand, that when on the strength of our own weak reason, we would attempt to account for the operations of nature, the relpect we owe the Creator should render us careful not to attribute to him a conduct which we can luppose unsuitable ro the ideas we have of his adorable wisdom; and in thjs view I think the system in question faulty.'

It will perhaps be objected to me, that what I here condemn as a fault in the System of Leewenhoeck we have nevertheless very frequent examples of in plants, which produce incomparably more' feeds than are neceflary for the preservation of their species, and of which a great part perishes without having contributed to this purpose. But if we bestow a little attention we sliall find that this example has no relation to the present case. For besides that there is no proportion between the number of spermatic worms which are produced in a single animal, and that of the seeds produced by the most fertile plants, the seeds ot vegetables are not destined merely for the preservation of the species, they are likewise destined 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 •'•' " , ' '■ , perish" jperish in the Uterus; can be of the fame use there. Add to this, that as plants have not the power of sowing their seeds in the earth, and that thus after they are stud, many of ,hem perish far want of being sown, it was necessary that plants should produce a quantity of seed sufficient to make up for this loss; besides we may fay that if any feeds perish, this happens only by accident. There is hardly any feed which, when thrown into the ground, does not produce a plant j but it is quite otherwise with spermatic worms. If they perish it is by necessity, and of so many hundreds of millions which enter inta the place said to be destined to receive them; there are only a few which, according to the iystem of Leeuwenhoeck, can become large animals. , ,

To all these difficulties which regard animal? in general,therc 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 ask what is the nature of the foul which animates them? Is it the foul of a brute? Is it a foul endowed with reason? If it be the soul of a brute; then is man composed of three distinct principles, a body* the foul of a brute, and a foul endowed with reason*. This 1 is what I suppose the advocates for the system of Leeuwenhoeck will not admit, and which would indeed be an opinion too singular 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 so many myriads of rational fouls, all except one or two destined to destruction f Would that accord with the notions we entertain of his infi * nite wisdom? I shall be told perhaps, that while these souls reside in the animalcules, they have not yet acquired rea* son, 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 disciple of Wolfius would reason. But this would not remove all the difficulty. The foul of the animalcule would always be essentially the fame with that of man ; it would always be a foul capable of receiving the perception of objects as they should be presented to it, and of reflecting on those objects. All the difference would be, that in the body of the animalcule those objects would be presented to it fewer in number and more obscurely; but this defect, which proceeds from the condition and imperfection of the body

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