Effects of Castration in Insects 



409 



stoma {e.g., in M. pulvinar von GrafF). In these striking exam- 

 ples the animal is only potentially hermaphroditic, since function- 

 ally it exhibits seasonal gonochorism through phasic castration 

 of the ovaries during its youth and of the testes during its adult 

 stages. 



B. Geoffrey Smith ('05 a, '09) has called attention to a very 

 striking form of phasic castration in decapod Crustacea: "Dur- 

 ing the breedmg season the males of Inachus mauritanicus fall 



Fig. 4. Males of Inachus mauritanicus. A small breeding male with swollen chelae; B non- 

 breeding male, with slender chelae; C, large breeding male with swollen chels. (Afier Geoffrey 

 Smith.) 



into three chief categories : Small males with swollen chelae (Fig. 

 4.J), middle sized males with flattened chelae {B), and large males 

 with enormously swollen chelae (C). On dissecting specimens 

 of the first and third categories it is found that the testes occupy 

 a large part of the thoracic cavity and are full of spermatozoa, 

 while in the middle-sized males with female-like chelae the tes- 

 tes appear shrivelled and contain few^ spermatozoa. These no..- 

 breeding crabs are, in fact, undergoing a period of active growth 

 and sexual suppression before attaining the final stage of devel- 



