CHAPTEB XIY. 



SEX. 



THE causes that determine sex have been a subject 

 of speculation from the earliest times. The theories 

 that were first framed, in accordance with some fan- 

 cied analogy, as an expression of the laws of the or- 

 ganization, have been repeatedly revived in their orig- 

 inal form, without adding to our knowledge of the 

 conditions that determine the result. 



From the fact that there are two testicles and two 

 ovaries in the higher animals, symmetrically placed, 

 one on each side of the median line of the body, it 

 was supposed that the right ovary and testicle were 

 concerned in the production of males, and the left in 

 the production of females. 



Physiologists have long known that this theory 

 had no foundation in fact, as males with one testicle 

 and females with one ovary produce offspring of 

 both sexes. The following case, reported by Prof. 

 Marzolo, of Padua, is of particular interest: "In a 

 patient, thirty-five years of age, the left ovary was 

 removed for cystic tumor. The woman recovered 

 from the operation, and became pregnant about a 

 year after. She was delivered at full term of twins, 



