402 William Morton fVheeler 



from the males by their ovipositors. He intends to remove the 

 spermatophore glands from some of the males of this series and also 

 from some uncastrated males and to report on the results in a 

 further publication. 



2. Alimentary Castration 



The best examples of this form of castration are to be found 

 among the social Hymenoptera, i.e., among the social wasps, 

 bees and ants. In these insects the majority of the female larvae 

 in each colony become what are called workers, because they are 

 fed on a limited diet, grow very slowly, pupate more or less 

 prematurely and hence as adults, or imagines are smaller in stat- 

 ure than the normal females of their respective species. These 

 workers are also distinguished by other morphological and etho- 

 logical peculiarities. Owing to their inadequate nourishment as 

 larvae, their ovaries are, as a rule, in a very rudimentary condition. 

 Very striking examples of this alimentary castration are seen in 

 the incipient colonies of ants, while the mother queen is bringing 

 up her first diminutive brood of workers, in the species of Carebara, 

 the queens of which are more than looo times as large as their 

 sterile offspring, and in Pheidologeton, in which there is nearly as 

 great a difference beween the stature of the queen and that of 

 the smallest workers. In bumblebees, honey-bees, social wasps 

 and most ants this difference is less pronounced, but it is never- 

 theless perceptible and clearly traceable to larval starvation. 

 Opinions differ as to whether the other characters peculiar to the 

 worker forms of these insects are the result of underfeeding, but 

 it is evident that none of these can be regarded as an approach to 

 the male type of structure. In other words, notwithstanding the 

 very decided inhibitory effect of larval starvation on the develop- 

 ment of the ovaries in the adult workers of the social Hymenop- 

 tera, the soma does not tend to become like that of the male, but 

 merely departs to a greater or less degree from that of the female 

 type. This departure is usually in the direction of greater simpli- 

 fication and is most pronounced in the ants, the workers of which 

 are wingless, have a smaller and much simpler thorax and smaller 

 eyes and ocelli. 



