408 William Morton Wheeler 



Nutricial castration is not confined to the social insects but 

 occurs also in mammals during the periods of gestation and lac- 

 tation and in birds during incubation, as the result of a very simi- 

 lar inability of the organism to expend in reproduction the ener- 

 gies demanded by the exigencies of the nursing function. 



^. Phasic Castration. 



The forms of sterility which I include under this term, though 

 temporary, cannot be sharply distinguished from the cases of 

 alimentary and nutricial castration, since both of these may be 

 abolished during ontogenetic development and yield to a fer- 

 tile phase, as, e.g., when worker ants become gynaecoid and nym- 

 phal termites become supplemental males and females. We may, 

 indeed, say that the great majority of animals exhibit alimentary 

 castration during their embryonic, larval and juvenile stages, but 

 that this is not universally true is shown by the many examples 

 of neotenia and pedogenesis scattered through the animal king- 

 dom. There are, however, several cases of temporary castra- 

 tion which, though intimately dependent on the trophic condition 

 of the individual nevertheless do not properly fall in the categories 

 previously considered. The following may serve as examples: 



A. Many hermaphroditic animals are protandric, /. e., develop 

 only their male reproductive organs at a very early stage and do 

 not mature their female reproductive organs till after the testes 

 are partly or wholly exhausted. Some of the most extreme cases 

 of this phenomenon are seen in the epicarid Crustacea and in 

 the singular parasitic worms of the genus Myzostoma. In the 

 crustacean Danalia the individual becomes a functional male 

 while it is still a minute and active larva. Later this form at- 

 taches itself to the abdomen of a crab, loses its limbs, and develops 

 a long proboscis which penetrates the tissues of its host. The 

 abundant nutriment thus acquired enables the parasite to grow 

 rapidly. Its ovaries then begin to enlarge, while the remains of 

 its testes degenerate and are devoured by phagocytes, and the 

 creature becomes a female. A very similar condition occurs, 

 'ds I showed several years ago ('96) in certain species of Myzo- 



