70 Bulletin American Museum of Natural Hi^ti ry. [Yol. XXIII, 



7. In the preceding cases, as I have shown in the first part of this article, 

 the ants undergo a pecuUar structural modification as the result of tolerating 

 parasites that bring about unusual perturbations in the trophic status of 

 the colony. When ants themselves become parasitic on other ants a similar 

 perturbation results, but in these cases the morphological effects are con- 

 fined to the parasitic species and do not extend to their hosts. This must be 

 attributed to the fact that the parasitizing species live in affluence and are 

 no longer required to take part in the arduous and exacting labors of the 

 colony. Under such circumstances the inhibitory effects of nutricial castra- 

 tion on the development of the ovaries of the workers are removed and there 

 is a tendency for this caste to be replaced by egg-laying, gynsecoid individuals 

 or by ergatogynes, or for it to disappear completely. These effects are 

 clearly visible in nearly all parasitic ants. In the European Tomognathus 

 sublcevis, for example, the only known females are gynsecoid workers. In 

 the American Leptothorax emersoni, as I have shown, ^ gynsecoid workers and 

 ergatogynes are unusually abundant while the true females seem to be on 

 the verge of disappearing. Among the typical amazon ants (Polyergus 

 rufescens) of Europe, ergatogynes are not uncommon. In Strongylognathus 

 testaceus the worker caste seems to be dwindling, while in several perma- 

 nently parasitic genera {Anergates, Wheeleria, Epcecus, Epipheidole and 

 Sympheidole) it has completely disappeared. Only one cause can be as- 

 signed to these remarkable effects — the abundance of food with which the 

 parasites are provided by their hosts. 



8. In the Ponerinae and certain Myrmicinse, like Pheidole, Pogono- 

 myrmex, and Aphcenogaster, 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 altogether to account for the uniform 

 and precise morphological results that we witness in the personnel of the 

 various colonies. Moreover, accurate determination of the food supply 

 by the workers must be quite impossible in cases like that of the Pachy- 

 condyla larva attended by the commensal Metopina which surreptitiously 

 consumes a portion of the proferred food. 



9. The intimate dependence of the appearance of the dift'erent 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 major- 



1 Ethological Observations on an American Ant (Leptliorax Emersoni Wlieeler), Arch. f. 

 Psych, u. Neurol., II, 1903, p. 6. 



