GENERATION AND DEVELOPMENT. 197 



the possibility of hen partridges being impregnated by the 

 breath of the cock.* This was an old popular belief. 



In G. ^. i. c. 21, 7296, he illustrates his views by saying 

 that what the female contributes to the embryo is like the 

 wood which is formed into a couch by the carpenter's art, 

 or like the material of a sphere of wax, the form due to the 

 art of the carpenter, in one case, or of the modeller, in the 

 other, being comparable with the influence contributed by 

 the male, 



Aristotle's reasoning on these questions is philosophical 

 and powerful, but without the aid of the microscope such 

 questions could not be solved satisfactorily. The ova con- 

 tributed by the female are now known to be exceedingly 

 complex in structure, and not to be composed of merely 

 passive formative material. Again, considering the nature 

 of the catamenia and the fact that, in H. A. vii. c. 2, and in 

 other passages, he shows that he understood the purifying 

 nature of them, it is difficult to understand why he should 

 have considered them to represent, in the female, the sperm 

 of the male. There seems to be no doubt about this opinion, 

 and he attempts to explain that the catamenial fluid is a 

 sperm which has not been fully elaborated.! 



It is well known by embryologists that, until the re- 

 searches of Weissmann and others, the theory of epigenesis 

 was generally held to be true. This theory was foreshadowed 

 by Aristotle, and elaborated by Harvey, Wolff, and Blumen- 

 bach. According to this theory, the parts of the young 

 animal are developed as new formations in the embryo, and, 

 in contradistinction to the old evolution theory, do not exist 

 as pre-formed parts in miniature, either in the spermatozoon 

 or in the ovum. Aristotle's views are set out, inG. A. ii. c. 1, 

 in such a way as to show that he was not quite free from 

 a belief in the existence of pre-formed parts. He seems to 

 have believed that the germ contained some kind of vital 

 principle, and was so constituted that, the vital principle 

 having started the process of development, this process 

 went on, like an automaton, the parts of the young 

 animal being produced one after another, in the way sug- 

 gested in the so-called verses of Orpheus, in which it is 

 stated that the parts are formed in succession, like the knots 

 of a net. The heart, having in itself a source of increase, 

 was generated first, according to Aristotle, and then other 



- H, A. vi. c. 2, s. 9. f G. A. iv. c. 5, 774rt. 



