332 ON GENERATION. 



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. 



