ON GENERATION. 191 



course, fruitful eggs are deposited, the rudiments or matter of 

 which did not exist at the time of the communication. 



With a view to explaining how the spermatic fluid of the 

 cock renders eggs fecund, Fabricius says : l " Since the semen 

 does not appear in the egg, and yet is thrown into the uterus 

 by the cock, it may be asked why this is done if the fluid does not 

 enter the egg ? Farther : if not present in the egg, how is that 

 egg made fruitful by the spermatic fluid of the cock which it yet 

 does not contain ? My opinion is that the semen of the cock 

 thrown into the commencement of the uterus, produces an in- 

 fluence on the whole of the uterus, and at the same time ren- 

 ders fruitful the whole of the yelks, and finally of the perfect eggs 

 which fall into it ; and this the semen effects by its peculiar 

 property or irradiative spirituous substance, in the same manner 

 as we see other animals rendered fruitful by the testicles and 

 semen. For if any one will but bring to mind the incredible 

 change that is produced by castration, when the heat, strength, 

 and fecundity are lost, he will readily admit that what we have 

 proposed may happen in reference to the single uterus of a 

 fowl. But that it is in all respects true, and that the faculty 

 of impregnating the whole of the ova, and also the uterus itself, 

 proceeds from the semen of the cock, appears from the custom 

 of those housewives who keep hens at home but no cock, that 

 they commit their hens for a day or two to a neighbour's cock, 

 and in this short space of time the whole of the eggs that will 

 be laid for a certain season are rendered prolific. And this 

 fact is confirmed by Aristotle, 2 who will have it that, among 

 birds, one intercourse suffices to render almost all the eggs 

 fruitful. For the fecundating influence of the seminal fluid, 

 as it cannot exhale, so is it long retained in the uterus, to 

 which it imparts the whole of its virtue ; nature herself stores 

 it up, placing it in a cavity appended to the uterus, near the 

 fundament, furnished with an entrance only, so that, being there 

 laid up, its virtue is the better preserved and communicated to 

 the entire uterus." 



I, however, suspected the truth of the above views, all the 

 more when I saw that the words of the philosopher referred 

 to were not accurately quoted. Aristotle does not say that 



1 Op. cit. i>. 37. 2 De Gen. Anim. lib. iii, c. 1. 



