INTRODUCTION. 



IT will not, I trust, be unwelcome to you, candid reader, if 

 I yield to the wishes, I might even say the entreaties, of many, 

 and in these Exercises on Animal Generation, lay before the 

 student and lover of truth what I have observed on this subject 

 from anatomical dissections, which turns out to be very dif- 

 ferent from anything that is delivered by authors, whether 

 philosophers or physicians. 



Physicians, following Galen, teach that from the semen of 

 the male and female mingled in coition the offspring is pro- 

 duced, and resembles one or other, according to the predomi- 

 nance of this one or of that ; and farther, that in virtue of the 

 same predominance, it is either male or female. Sometimes 

 they declare the semen masculinum as the efficient cause, and 

 the semen femininum as supplying the matter ; and sometimes, 

 again, they advocate precisely the opposite doctrine. Aris- 

 totle, one of Nature's most diligent inquirers, however affirms 

 the principles of generation to be the male and the female, she 

 contributing the matter, he the form; and that immediately 

 after the sexual act the vital principle and the first particle of 

 the future foetus, viz. the heart, in animals that have red blood, 

 are formed from the menstrual blood in the uterus. 



But that these are erroneous and hasty conclusions is easily 

 made to appear: like phantoms of darkness they suddenly 

 vanish before the light of anatomical inquiry. Nor is any long 



