48 Annals Entomological Society of America [Vol. I, 



typical female form of the species, the problem of polymorphism 

 is to account for the various worker forms, and those like the sol- 

 diers, pseudogynes and ergatoid females which are more or less 

 intermediate between the worker and the queen. The ergato- 

 morphic males are regarded as having inherited worker characters. 

 Thus the problem of polymorphism centers in the development of 

 the worker. It must suffice in this place to give the briefest pos- 

 sible statement of the views of the various authors who have 

 endeavored to account for the development of this caste. These 

 authors may be divided into three groups: 



1 . Those who believe, with Weismann, that the various castes 

 are represented in the egg by corresponding units (determinants) . 

 Fertilization is then regarded as the stimulus which calls^the fe- 

 male determinants into activity and meager feeding the stimulus 

 which arouses the worker-producing determinants in the young 

 larvae arising from fertilized eggs. Such an explanation is ob- 

 viously little more than a restatement, or "photograph" of the 

 problem. It seeks to account for the adaptive characters of the 

 worker forms through natural selection acting on fortuitous con- 

 genital variations. 



2. Those who believe, with Herbert Spencer, that there is 

 no such preformation of the various female castes, but that these 

 are produced epigenetically by differences in the feeding of the 

 larvae. The workers simply arise from larvae that are inadequate- 

 ly fed but are nevertheless able to pupate and hatch when only a 

 part of their growth has been completed. This is not, like the 

 preceding view, a restatement of the problem, since the modifica- 

 tions induced by inadequate feeding are conceived as somatic 

 and not as germinal, but it fails to explain how the worker caste 

 acquires its adaptive characters, unless this caste is supposed to 

 reproduce with sufficient frequency to transmit acquired somatic 

 modifications to the germ-plasm of the species. 



3. A third group of investigators believes, with Emery, that 

 the germ-plasm of the social Hymenopteron is indeed implicated 

 in the phenomenon, not* however, as possessing separate sets of 

 determinants, but as being in a labile or sensitive condition and 

 therefore capable of being deflected along different developmental 

 paths by differences in the trophic stimuli acting on the larva. 

 According to Emery, "the peculiarities in which the workers differ 

 from the corresponding sexual forms are, therefore, not innate or 

 blastogenic, but acquired, that is somatogenic. Nor are they 



