JATS. 



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, L'ainpo- 

 notits, Phcidolc, etc., the workers or desmergates vary in size, must be 

 regarded as the result of variable quantitative feeding in the larval 

 stage. Mere we are confronted with the same conditions as \Veismann 

 observed in prematurely pupating blow-flies, and entomologists have 

 noticed in many other insects. Such variations are of the fluctuating 

 tvpe and are therefore attributable to the direct effects of the environ- 

 ment. The soldier and worker, however, differ from the queen in the 

 absence of certain characters, like the wings, wing-muscles, sperma- 

 theca, some of the ovarian tubules, etc., and the presence of other 

 characters, like the peculiar shape of the head and mandibles. In these 

 respects the sterile castes- may be regarded as mutants, and \Yeis- 

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

 conditions, such as feeding, is in full accord with de Yries'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 prin- 

 ciple. It is certain that very plastic insects, like the ants, have devel- 

 oped 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 suppression of certain organs that require for their 

 formation more substance than the underfed larva is 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 hand, has not been satis- 

 factorily established. The conditions in the termites, which are often 

 cited as furnishing proof of this connection, are even more complicated 

 and obscure than those of the social Hymenoptera. While Grass! and 

 Sandias (1893) an ^ Silvestri (1901) agree with Spencer in regarding 

 feeding as the direct cause of the production of the various castes. 

 Herbst (1901), who has reviewed the work of the former authors, 

 shows that their observations are by no means conclusive ; and Heath 

 ' i)Q2) makes the following statement in regard to his experiments on 

 Californian termites : "For months I have fed a large number of termite 

 colonies of all ages, with or without royal pairs, on various kinds and 

 amounts of foods proctodaeal food dissected from the workers or in 

 other cases from royal forms, stomadaeal food from the same sources, 

 sawdust to which different nutritious ingredients have been added 



