StXVi INTRODUCTORY OBSERVATIONS. 



The theories of generation which thefe pecu<- 

 iiarities have created are various ; and all, even 

 the mod inconfiflent and chimerical, have had 

 partifans. Perhaps the fame difficulty does not 

 attend a probable conjedlure, not to go fo far as 

 ■explanation, of that generation, which is eifefted 

 by means of a fluid and of eggs. When the fe- 

 male approaches maturity, and often long before 

 it, fubftances refembling eggs, or which really are 

 fo, appear ; and in the male is fecreted that parti- 

 cular fluid which is peopled by numberlefs ver- 

 miculi. Immediately after they were difcovered, the 

 charge of perpetuating animated beings was com- 

 mitted to them : it was generally believed that e- 

 -very animal originated from a vermicule. But it is 

 now univerfally known that the foetus belongs to 

 the mother alone ; that It pre-exifts fecundation ; 

 and lies dormant until It is called into exiftence. 

 Eggs have been rendered prolific ; and animals, 

 which require copulation to propagate their 

 young, have been artificially fecundated, that is, 

 without interpofitlon of the male. It is even 

 faid that this ftrange experiment has fuc<:eeded in 

 mankind. Still it is to be explained,'why of twenty 

 or thirty eggs, as in the human female, only one 

 is impregnated at a time, and why ten or fifteen 

 may be impregnated in a female quadruped ; 

 more efpecially, if generation is eflefted by ab- 



forption, 



