Page:The Works of William Harvey (part 1 of 2).djvu/432

 rated from a small quantity of seminal matter, whilst the mat- ter which is taken up as food and nourishment is very large ; so a small chalaza suffices for the generation of a chick, and the rest of the matter contained in the egg goes to it in the shape of nutriment." From which it is obvious, that he sought for some such ' prepared matter ' in the egg, whence the chick should be incorporated; mainly, as it seems, that he might not be found in contradiction with Aristotle's definition of an egg, 1 viz. : as " that from part of which an animal is engen- dered; and the remainder of which is food for the thing engendered." This of Fabricius, therefore, has the look of a valid argument, namely, " Since there are only three parts in the egg, the albumen, the vitellus, and the chalazae ; and the two former alone supply aliment ; it necessarily follows, that the chalazse alone are the matter from which the chick is con- stituted."

Thus, our learned anatomist, blinded by a popular error, seeking in the egg for some particular matter fitted to engender the chick distinct from the rest of the contents of the egg, has gone astray. And so it happens to all, who forsaking the light, which the frequent dissection of bodies, and familiar converse with nature supplies, expect that they are to under- stand from conjecture, and arguments founded on probabilities, or the authority of writers, the things or the facts which they ought themselves to behold with their own eyes, to perceive with their proper senses. It is not wonderful, therefore, when we see that we have so many errors accredited by general consent, handed down to us from remote antiquity, that men otherwise of great ingenuity, should be egregiously deceived, which they may very well be, when they are satisfied with taking their knowledge from books, and keeping their memory stored with the notions of learned men. They who philoso- phise in this way, by tradition, if I may so say, knoAv no better than the books they keep by them.

In the egg then, as we have said, there is no distinct part or prepared matter present, from which the foetus is formed ; but in the same way as the apex or gemmule protrudes in a seed ; so in the egg, there is a macula or cicatricula, which

1 Hist. Anim. lib. iii, cap. 8.