Basis of Sex Determination 219 



fetus can be injected from the other. The arterial circula- 

 tion of each also overlaps the venous territory of the other, 

 so that a constant interchange of blood takes place. If 

 both are males or both are females no harm results from 

 this; but if one is male and the other female, the reproductive 

 system of the female is largely suppressed, and certain male 

 organs even develop in the female. This is unquestionably to 

 be interpreted as a case of hormone action. 



The reproductive system of these sterile females is for 

 the most part of the female type, though greatly reduced. 

 The gonad is the part most affected; so much so that most 

 authors have interpreted it as testis. 



It should be added, however, that this result cannot 

 at present be generalized, since in the hermaphrodites 

 the specific hormones of both sexes must circulate 

 without suppressing each other's efficiency. 



All these facts indicate that certain substances 

 secreted by the ovaries or testes may inhibit the de- 

 velopment of certain sexual characters of the opposite 

 sex. When these inhibitions are partly or entirely 

 removed the secondary sexual characters of the opposite 

 sex may appear. This fact may also be interpreted as 

 an indication of a latent hermaphroditism and if this 

 be correct the real and latent hermaphrodites differ 

 only by the degree of inhibition for one sex, this inhibi- 

 tion being lacking or less complete in the real than in 

 the latent hermaphrodite. 



In the light of this conclusion the observations on 

 the regeneration of both ovaries and testicles which 

 Janda observed in a hermaphroditic worm, Criodrilus 



