POLYMORPHISM. 103 



of its parent. If this moment can be detected very early in the devel- 

 opment he will be inclined to project the morphological differentiation 

 back into the germ-plasm and to regard the efforts of the physiologist 

 as relatively unimportant if not altogether futile. Now in his study of 

 the social insects the embryologist is at a serious disadvantage, since 

 he has hitherto been unable to distinguish any prospective worker or 

 queen characters in the eggs or even in the young larvae. Compelled, 

 therefore, to confine his attention to the older larvae, whose develop- 

 ment as mere processes of histogenesis and metamorphosis throws little 

 or no light on the meaning of polymorphism, he is bound to leave 

 the physiologist in possession of the problem. 



The physiologist, in seeking to determine whether there is in the 

 environment of the developing social Hymenopteron any normal 



FIG. 64. Gynandromorph of Ef>if>heidole inqitilina ; male on the left, female on the 



right side. (Original.) 



stimulus that may account for the deviation towards the worker or 

 queen type, can hardly overlook one of the most important of all 

 stimuli, the food of the larva. At first sight this bids fair greatly to 

 simplify the problem of polymorphism, for the mere size of the adult 

 insect would seem to be attributable to the quantity, its morphological 

 deviations to the quality of the food administered to it during its 

 larval life. Closer examination of the subject, however, cannot fail 

 to show that larval alimentation among such highly specialized animals 

 as the social insects, and especially in the honey-bees and ants, where 

 the differences between the queens and workers are most salient, is a 

 matter of considerable complexity. In the first place, it is evident that 

 it is not the food administered that acts as a stimulus but the portion 



