1907.] Wheeler, The Polymorphism oj Ants. 67 



The physiologist, in seeking to deterniine wliether there is in the envi- 

 ronment of the developing social Hymenopteron any normal 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 might 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 subject 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 of it 

 that is assimilated by the living tissues of the larva. In other Avords, the 

 larva is not altogether a passive organism, compelled to utilize all the food 

 that is forced upon it, but an active agent capable, at least to a certain extent, 

 of determining its own development. And the physiologist might have 

 difficulty in meeting the assertion, that the larva utilizes only those portions 

 of the proffered food which are most conducive to the specific predetermined 

 trend of its development. In the second place, while experiments on many 

 organisms have shown that the quantity of assimilated food may produce 

 great changes in size or stature, there is practically nothing to show that 

 even very great differences in the quality of the food can bring about morpho- 

 logical differences of such magnitude as those which separate the queens 

 and workers of many ants.^ 



These more general considerations are reinforced by the following 

 inferences from the known facts of larval feeding: 



1. There seems to be no valid reason for supposing that the morphogeny 

 of the queens of the social Hymenoptera depends on a particular diet, since 

 with the possible exception of the honey and stingless bees, to be considered 

 presently, they differ in no essential respect from the corresponding sexual 

 phase of the solitary species. In both cases they are the normal females 

 of the species and bear the same morphological relations to their males 

 quite irrespective of the nature of their larval food. Hence, with the above 

 mentioned exception of the honey and stingless bees, the question of the 

 morphogenic value of the larval food may be restricted to the worker forms. 



2. Observation shows that although the food administered to the 



1 Emery (Le Polymorphisme, etc., loc. cit.) has called attention to the importance of the assimi- 

 lative powers of the ant larva itself, quite irrespective of the quantity and quality of the food 

 administered by the nurses — a very obscure physiological pheiionienon, l)nt not wiliiout atudo- 

 gies in otiier animals and especially in plants, which may assume a dwarfeil hal)it us under api)ar- 

 ently very favorable trophic conditions. The production of 'high' antl 'low' males in Scaralj*i(l 

 and'Lucanid beetles seems to be of the same nature. 



