Nevertheless, although I think that Perrier has made good his position thus far, that his hypothesis fails to account for some of the instincts which are manifested by neuter insects, such as those which, so far as I can see, must necessarily be supposed to have originated after the breeding and working functions had become separated--seeing that they appear to have exclusive reference to this peculiar state of matters. Possibly, however, Perrier might be able to meet each of these particular instincts, by showing how they could have arisen out of simpler beginnings, prior to the separation of the two functions in question. There is no space to consider such possibilities in detail; but, until this shall have been done, I do not think we are entitled to conclude that the phenomena of instinct as presented by neuter insects are demonstrably incompatible with the doctrines of Lamarck--or, that these phenomena are available as a logical proof of the unassisted agency of natural selection in the case of instincts in general[54]. [54] [See H. Spencer, _The Inadequacy of Natural Selection, A Rejoinder to Professor Weismann_, Contemp. Rev. 1893; and _Weismannism once more_, Ibid. Oct. 1894; Weismann, _The All-sufficiency of Natural Selection_, Ibid. 1893; and _The Effect of External Influences upon Development_, "Romanes Lecture" 1894: also _Neuter Insects and Lamarckism_, W. Platt Ball, Natural Science, Feb. 1894, and _Neuter Insects and Darwinism_, J. T. Cunningham, Ibid. April 1894. C. Ll. M.] (B.) _Inherited Effects of Use and of Disuse._ There is no doubt that Darwin everywhere attaches great weight to this line of evidence. Nevertheless, in my opinion, there is equally little doubt that, taken by itself, it is of immeasurably less weight than Darwin supposed. Indeed, I quite agree with Weismann that the whole of this line of evidence is practically worthless; and for the following reasons. The evidence on which Darwin relied to prove the inherited effects of use and disuse was derived from his careful measurements of the increase or decrease which certain bones of our domesticated animals have undergone, as compared with the corresponding bones of ancestral stocks in a state of nature. He chose domesticated animals for these investigations, because, while yielding unquestionable cases of increased or diminished use of certain organs over a large number of sequent generations, the results were not complicated by the possible interference of natural selection on the one hand, or by that of the economy of nutrition on the other. For "with highly-fed domesticated animals there seems to be no economy of growth, or any tendency to the elimination of superfluous details[55];" seeing that, among other considerations pointing in the same direction, "structures which are rudimentary in the parent species, sometimes become partially re-developed in our domesticated productions[56]."