670 APPENDIX B. 



and their appendages must have taken place during the transition 

 from arboreal habits to terrestrial habits ; and dwindling of the 

 little toe is an obvious consequence of disuse, at the same time 

 that enlargement of the great toe is an obvious consequence of 

 increased use. 



The entire argument based on the unlike forms and instincts 

 presented by castes of social insects is invalidated by an omission. 

 Until probable conclusions are reached respecting the characters 

 which such insects brought with them into the organized social 

 state, no valid inferences can be drawn respecting characters de- 

 veloped during that state. 



A further large error of interpretation is involved in the as- 

 sumption that the different caste-characters are transmitted to 

 them in the eggs laid by the mother insect. While we have 

 evidence that the unlike structures .of the sexes are determined by 

 nutrition of the germ before egg-laying, we have evidence that 

 the unlike structures of classes are caused by unlikenesses of nutri- 

 tion of the larvae. That these varieties of forms do not result 

 from varieties of germ-plasms, is demonstrated by the fact that 

 where there are varieties of germ-plasms, as in varieties of the 

 same species of mammal, no deviations in feeding prevent display 

 of their structural results. 



For such caste-modifications as those of the Amazon-ants, 

 which are unable to feed themselves, there is a feasible explana- 

 tion other than Professor Weismann's. The relation of common 

 ants to their domestic animals — aphides and coccids — which yield 

 them food on solicitation, does not differ widely from this rela- 

 tion between these Amazon-ants and their domestic animals — the 

 slave-ants. And the habit of being fed, contracted during the 

 first stages of their parasitic life, when there were perfect males 

 and females, may, during . that stage, have become established by 

 inheritance. Meanwhile the opposed interpretation — that this in- 

 capacity has resulted from the selection of those ant-communities 

 the queens of which laid eggs that had so varied as to entail this 

 incapacity — implies that a scarcely appreciable economy of nerve- 

 matter advantaged the stirp so greatly as to cause it to spread 

 more than other stirps : an incredible supposition. 



As the outcome of these alternative interpretations we saw 

 that the argument respecting the co-adaptation of co-operative 

 parts, which Professor Weismann thinks is furnished to him by 

 the Amazon-ants, disappears. The ancestral ants were conquering 

 ants. These founded the communities ; and hence those members 

 of the present communities which are most like them are the 

 Amazon-ants. If so, the co-adaptation of the co-operative parts 

 was effected by inheritance during the solitary and semi-social 

 stages. Even were there no such solution, the opposed solution 



