ON GENERATION. 317 



rudiments of all eggs are produced in the ovary and take their 

 increase, seems to be the very same from which all the other 

 parts of the hen, namely, the fleshy, nervous, and bony struc- 

 tures, as well as the head and the rest of the members, are 

 nourished and grow. Nourishment is in fact conveyed to each 

 single papula and yelk contained in the ovary by means of 

 vessels, in the same way precisely as to all the other parts of 

 the hen. But the place where the egg is provided with mem- 

 branes, and perfected by the addition of the chalazse and shell, 

 is the uterus. 



But that the hen neither emits any semen during inter- 

 course, nor sheds any blood into the cavity of the uterus, and 

 that the egg is not formed in the mode in which Aristotle sup- 

 posed a conception to arise, nor, as physicians imagine, from 

 a mixture of the seminal fluids; as also that the semen of the 

 cock does not penetrate into, nor is attracted towards, the cavity 

 of the uterus of the hen, is all made manifestly clear by this 

 one observation, namely, that after intercourse there is nothing 

 more to be found in the uterus, than there was before the act. 

 And when this shall have been afterwards clearly established 

 and demonstrated to be true of all kinds of animals, which 

 conceive in a uterus, it will at the same time be equally evi- 

 dent, that what has hitherto been handed down to us from all 

 antiquity on the generation of animals, is erroneous ; that the 

 foetus is not constituted of the semen either of the male or 

 female, nor of a mixture of the two, nor of the menstrual blood, 

 but that in all animals, as well in the prolific conception as 

 after it, the same series of phenomena occur as in the genera- 

 tion of the chick from the egg, and as in the production of 

 plants from the seeds of their several kinds. For, besides 

 that, it appears the male is not required as being in himself 

 agent, workman, and efficient cause ; nor the female, as if she 

 supplied the matter ; but that each, male as well as female, may 

 be said to be in some sort the operative and parent ; and the 

 foetus, as a mixture of both, is created a mixed resemblance 

 and kind. Nor is that true which Aristotle often affirms, and 

 physicians take for granted, namely, that immediately after 

 intercourse, something either of the foetus or the conception 

 may be found in the uterus, (for instance, the heart, the " three 

 bullse," or some other principal part,) at any rate something 



