I4O ROBERT CHAMBERS, JR. 



some degenerates. By inference from other groups of insects 

 this is the male-producing class. The other class produces 

 functional sperm which, entering the egg, give rise to females 

 only. These sperm correspond to the female-producing sperm 

 of other insects. 



In Simocephahis no accessory chromosome is to be distin- 

 guished, the sperm being apparently all alike in their chromo- 

 some number. 



No means as yet have been found to distinguish two classes. 

 The presence of degenerating sperm in the lumen of the testis 

 does not necessarily prove the existence of two classes of sperm. 

 However, as the functional sperm enter eggs which develop only 

 into females, the assumption is permissible that these are the 

 female-producing sperm and that the male-producing sperm are 

 those which degenerate. 



