84 SEX 



very curious that only female crabs were 

 attacked, but Giard showed that many of the 

 apparent females were parasitised males. If 

 the victim be a female, there is no change of 

 structure or of instinct, except that she 

 cherishes the parasite instead of eggs which 

 are absent. 



Giard's work has been extended by that 

 of Geoffrey Smith, in a series of researches 

 remarkable for their thoroughness. In the 

 case of male crabs of the genus Inachus, for 

 instance, he found that castration, brought 



FIG. 15. Forms of Abdomen in a crab, Paehygrapsus. A, of 

 a female ; B, of a male ; C, of a parasitised male approxi- 

 mating to the female type. (After Geoffrey Smith.) 



about by Sacculina and the like, induced a 

 very striking expression of latent feminine 

 and female features. The crab developed 

 egg-carrying abdominal limbs like those of a 

 female and it produced eggs. The normal 

 crab is not in any sense a hermaphrodite, 

 but the effect of castration is the development 

 of the latent characters of the other sex. 



Potts has studied the castration of male 

 hermit-crabs by Peltogaster and of male 

 shore-crabs by Sacculina. In the former, 

 the male characters persisted; in the latter, 

 though the castration was incomplete, some 



