6 JOHN W. GOWEN. 



the freemartin is an undifferentiated male formed from the divi- 

 sion of a single male-producing egg. Clearly, on this basis, these 

 animals should be identical in appearance and the identical classes 

 in the groups female twins, male twins and male and female twins 

 should be large compared with those of the sister, sister class. As 

 this is not so, it becomes doubtful if the hypothesis adopted by 

 them will hold for the origin of the freemartin. 



