Eels, in paste made with flour, have no other origin than the union of the organic particles of the most essential parts of the grain: the first which appear are certainly not produced by many others; yet, although they have not been engendered, they engender others. By cutting them with the point of a lancet, we may perceive small eels come from their bodies in great numbers; the body of the animal appears to be only a sheath or bag which contains a multitude of other little animals, which perhaps are themselves only sheaths of the same kind, in which the organic matter assimilates, and takes the form of eels. There requires a great number of observations to be made to establish classes and races between such singular beings, which are at present so little known; there are some which may be regarded as real zoophytes, which vegetate, and at the same time appear to twirl and move like animals. There are some that at first appear to be animals, which afterwards join and form kinds of vegetables. A little attention to the decomposition of a grain of wheat infused in water will elucidate all I have asserted. I could add more examples, but I have related these only to point out the varieties there are in generation. There are certainly organized beings which we regard as animals, but which are not engendered by others of the same kind; there are some which are only a kind of machines, whose action is limited to a certain effect, and which can act but once in such a certain time, as those in the calmar; and there are others, as we have just remarked, which we can cause to act as long and as often as we please. There are vegetating beings which produce animated bodies, as the filaments of the human seed, from whence the active globules spring, and which move by their own powers. In the corruption, fermentation, or rather the decomposition of animal and vegetable substances, there are organized bodies which are real animals, and can propagate their like, although they have not been so produced. The limits of these varieties are perhaps still greater than we can imagine. We may extend our ideas, and exert every effort to reduce the effects of Nature to certain points, and class her productions to certain classes, yet an infinite number of links will always escape us. CHAPTER X. OF THE FORMATION OF THE FOETUS.