I J OL } 'MORPHISM. 1 07 



completely. These effects are clearly visible in nearly all parasitic 

 ants. In the European Harpagoxenus snblcvis, for example, the only 

 known females in certain localities are gynaecoid workers. In the 

 American Lepfothorax cnicrsoni, as I have shown (I9O3/J, gynaecoid 

 workers and ergatogynes are unusually abundant, while the true females 

 seem to be on the verge of disappearing. Among the typical amazon 

 ants (Polycrgus nifcsccns) of Europe, ergatogynes are not uncommon. 

 In Strongylognathus tcstaccns the worker caste seems to be dwindling, 

 while in several permanently parasitic genera (Anergates, Wheelerietta, 

 Epoccns, Epipheidole and Symphcidolc ) it has completely disappeared. 

 Only one cause can be assigned to these remarkable effects the 

 abundance of food with which the parasites are provided by their 

 hosts. 



8. In the Ponerinae and certain Myrmicinae, like Phcidole, Pogono- 

 inynnc.i' and Aphanogaster, the larvae are fed on pieces of insects or 

 seeds, the exact assimilative value of which as food can neither be 

 determined nor controlled by the nurses. And while they may perhaps 

 regulate the quantity of food administered, it is more probable that 

 this must fluctuate within limits so wide and indefinite as to fail alto- 

 gether to account for the uniform and precise morphological results that 

 we witness in the personnel of the various colonies (Fig. 51). More- 

 over, accurate determination of the food supply by the workers must be 

 quite impossible in cases like that of the Pachycondyla larva bearing 

 the commensal Metopina (see p. 412). 



9. The dependence of the different castes of the social insects on the 

 seasons may also be adduced as evidence of the direct effects of the 

 food supply in producing workers and queens. The latter are reared 

 only when the trophic condition of the colony is most favorable, and 

 this coincides with the summer months ; in the great majority of species 

 only workers and males are produced at other seasons. Here, too, the 

 cause is to be sought in the deficient quantity of food rather than in 

 its quality, which is in all probability the same throughout the year, 

 especially in such ants as the fungus-growing Attii. 



While these -considerations tend to invalidate the supposition that 

 qualitative feeding is responsible for the morphological peculiarities 

 of the worker type, they are less equivocal in regard to the morpho- 

 genic effects of quantitative feeding. Indeed several of the observa- 

 tions above cited show very clearly that diminution in stature and, in 

 pathological cases, even reversion to the worker form may be the direct 

 effect of underfeeding. To the same cause we may confidently assign 

 several of the atypical phases among ants, such as the micrergates, 

 microgynes, and micraners, just as we may regard the macrergates, 



