“I have now explained how, as I believe, the wonderful fact of two distinctly defined castes of sterile workers existing in the same nest, both widely different from each other and from their parents, has originated. We can see how useful their production may have been to a social community of ants, on the same principle that the division of labor is useful to civilized man. Ants, however, work by inherited instincts and by inherited organs or tools, whilst man works by acquired knowledge and manufactured instruments. But I must confess, that, with all my faith in natural selection, I should never have anticipated that this principle could have been efficient in so high a degree, had not the case of these neuter insects led me to this conclusion. I have, therefore, discussed this case, at some little but wholly insufficient length, in order to show the power of natural selection, and likewise because this is by far the most serious special difficulty which my theory has encountered. The case, also, is very interesting, as it proves that with animals, as with plants, any amount of modification may be effected by the accumulation of numerous, slight, spontaneous variations, which are in any way profitable, without exercise or habit having been brought into play. For peculiar habits confined to the workers or sterile females, however long they might be followed, could not possibly affect the males and fertile females, which alone leave descendants. I am surprised that no one has hitherto advanced this demonstrative case of neuter insects, against the well-known doctrine of inherited habit, as advanced by Lamarck.” We may dissent at once from Darwin’s statement which, he thinks, “proves that any amount of modification may be affected by the accumulation of numerous slight variations which are in any way profitable without exercise or habit having been brought into play”; we may dissent if for no other reason than that this begs the whole point at issue, and is not proven. It does not follow because in some colonies all intermediate stages of neuters exist, that in other colonies, where no such intermediate stages are present, these have been slowly weeded out by natural selection, causing to disappear all colonies slightly below the mark. It is this that begs the question. Because we can imagine that intermediate stages between the different castes may have been present, it neither follows that such fluctuating variations have been the basis for the evolution of the more sharply defined types, nor that the imagined advantage of such a change would have led through competition to the extermination of the other colonies. However much we may admire the skill with which Darwin tried to meet this difficulty, let us not put down the results to the good of the theory, but rather repeat once more Darwin’s own words at the end of this chapter, to the effect that the facts do not strengthen the theory. Sterility between Species