THE GENERATIVE GLANDS 367 



individuals will not show complete identity of habit, either imme- 

 diately after operation or later ; certain characteristics, such as 

 beard and the mammas, will develop in accordance with their 

 original sex. Castrated males grow a certain, though scanty., 

 amount of hair on the face. These results are accounted for by 

 the fact, that the sexual differentiation of the tissues probably takes 

 place during fcetal life through the agency of the already dif- 

 ferentiated genital glands, and that after suppression of the 

 genital glands the primitive beginnings of individual stigmata 

 continue to grow and attain a certain imperfect degree of develop- 

 ment. 



The same applies to Ondermann's much-quoted experiments 

 with Oeneria dispar, and those of Kellog with silk-worms. Cas- 

 tration of the caterpillar did not obliterate the signs of sexual 

 dimorphism in the butterfly. 



In all these cases, castration was performed at so late a period 

 that the possible influence of the genital gland upon the develop- 

 ment of the somatic stigmata was not entirely excluded. 



In order to decide the question as to whether the sex of the 

 soma is congenital or not, it would be necessary to extirpate the 

 undifferentiated sexual glands of the foetus. The only evidence 

 on this point is that supplied by Nature in the case of the so- 

 called parasitic castration of crustaceans. 



It has long been known that certain crabs are attacked by 

 parasites which belong to the isopods of the family Bopyrida?. 

 These parasites are never found in fully-developed male crabs 

 and for this reason it has been asserted that female crabs are 

 their only hosts. Giard, who investigated this question very 

 thoroughly, found that the Bopyridas enter their host only during 

 the early youth of the latter ; that they attack both male and 

 female individuals; and that they effect the destruction of the 

 genital glands of their host. The result of this early gonotomy 

 is that the host does not develop sexual characteristics of any 

 kind, but becomes neuter in every sense of the term. Even more 

 interesting is the fact that, in certain orders (Slenorynchus), the 

 males which have been castrated in this manner, after casting 

 their shell several times, assume the habit of the female type so 

 completely, that for a long time they were believed to be females 

 or were regarded as of a different species. I believe myself that 

 this remarkable occurrence is explained by the fact that the 

 invading parasites are females only, which attain to sexual 

 maturity within the body of their host, and that the female genital 

 gland of the parasite has a determining influence upon the de- 

 velopment of the sex characteristics of the host. 



It appears then, that we have to do here with an instance 

 of early castration accompanied by simultaneous transplantation 

 of the heterosexual genital gland, and the results seem to show 

 that the somatic sex characteristics are dependent upon the cells 

 of generation. 



