1907.] Wheeler, The Polymorphism of Ayits. 71 



ity 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, espe- 

 cially in such ants as the fungus-growing Attii and the seed storing Myrmi- 

 cinae. 



While these considerations tend to invalidate the supposition that quali- 

 tative feeding is responsible for the morphological peculiarities of the worker 

 type, they are less equivocal in regard to the morphogenic effects of quanti- 

 tative feeding. Indeed, several of the observations 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 atj^jical phases among ants, 

 such as the micrergates, microgynes, and micraners, just as we may regard 

 the raacrergates, macrogynes, and macraners as due to overfeeding. These 

 are, of course, cases of nanism and giantism, variations in stature, not in 

 form. Similarly, all cases in which, as in certain species of Formica, Cam- 

 ponotus, Pheidole, etc., the workers or desmergates vary in size, must be 

 regarded as the result of variable quantitative feeding in the larval stage. 

 Here we are confronted with the same conditions as Weismann observed 

 in the blow-flies and which entomologists have noticed in many other insects. 

 Such variations are of the fluctuating type and are therefore attributable 

 to the direct effects of the environment. The soldier and worker, however, 

 differ from the queen in the absence of certain characters, like the wings, 

 wing-muscles, spermatheca, some of the ovarian tubules, etc., and the 

 presence of other characters, like the peculiar shape of the head and mandi- 

 bles. In these respects the sterile castes may be regarded as mutants, and 

 Weismann's contention that such characters cannot be produced by external 

 conditions, such as feeding, is in full accord with de Vries's hypothesis. 

 His further contention, however, that they must therefore be produced by 

 natural selection need not detain us, since it is daily becoming more and 

 more evident that this is not a creative but an eliminative principle. It 

 is certain that the very plastic social insects, like the ants, have developed 

 a type of ontogeny which enables them not only to pupate at an extremely 

 early period of larval life, but also to hatch and survive as useful though 

 highly specialized members of the colony. It is quite conceivable that this 

 precocious pupation may be directly responsible for the complete suppres- 

 sion of certain organs that require for their formation more substance than 

 the underfed larva has been able to accumulate. At the same time it must 

 be admitted that a direct causal connection between underfeeding on the 

 one hand and the ontogenetic loss or development of characters on the other, 

 has not been satisfactorily established. The conditions in the termites. 



