56 Annals Entomological Society of America [Vol. I, 



large number of termite colonies of all ages, with or without royal 

 pairs, on various kinds and amounts of food — proctodseal food 

 dissected from the workers or in other cases from royal forms, 

 stomodaeal food from the same sources, sawdust to which different 

 nutritious ingredients have been added — but in spite of all I can- 

 not feel perfectly sure that I have influenced in any unusual wa}^ 

 the growth of a single individual. " 



This rather unsatisfactory answer to the c[uestion as to whether 

 quantity or quality of food or both, have an ergatogenic value, 

 has led some investigators to seek a solution along more indirect 

 lines. Thus O. Hertwig and Herbst suggest that the morphogenic 

 stimulus may be furnished by some internal secretion of the re- 

 productive organs. This, too, is possible, but owing to our very 

 imperfect knowledge of the internal secretions, even in the higher 

 animals, we are not in a position either to accept or reject this 

 suggestion. 



We ma}' conclude, therefore, that while the conception of the 

 worker type as the result of imperfect nutrition is supported by a 

 considerable volume of evidence, we are still unable to understand 

 how this result can take on so highly adaptive a character. Such 

 a concise effect can hardly be due to manifold and fluctuating 

 external causes like nutrition, but must proceed from some more 

 deeply seated cause within the organism itself. Of course, the 

 difficulty here encountered is by no means peculiar to polymor- 

 phism ; it confronts us at every turn as the all-pervading enigma 

 of living matter. 



An intensive study of the structure and habits of ants must 

 inevitably lead to a certain amount of speculation concerning the 

 phylogenetic development of their colonies. That these insects 

 have had communistic habits for ages is clearly indicated by the 

 fact that all of the numerous existing species are eminently social. 

 There can be little doubt, however, that they rose from forms with 

 habits not unlike those we find today in some of the solitary wasps, 

 such as the Bembecidae, or in the remarkable South African bees 

 of the genus Allodape. Unlike other solitary wasps, the females 

 of Bembex may be said to be incipiently social, since a number of 

 them choose a nesting site in common and, though each has her 

 own burrow, cooperate with one another in driving away intrud- 

 ers. Bembex has also taken an important step in the direction 

 of the social wasps not only in surviving the hatching of her 

 larva?, but also in visiting them from day to day for the pur- 

 pose of providing them with fresh insect food. 



