If to this it be said that in the above passage there is no special mention of _species_, the quibble would admit of a three-fold reply. In the first place, the quibble in question had never been raised. As already stated, it is only since the appearance of my own paper on _Physiological Selection_ that anybody ever thought of drawing a distinction between species and genera, such that while all specific characters must be held necessarily useful, no such necessity extends to generic characters. In the second place, that Darwin must have had specific characters (as well as generic) in his mind when writing the above passage, is rendered unquestionable by the fact that many of the instances of inutility adduced by Nägeli and Broca have reference to specific characters. Lastly, as shown in the passages previously quoted from the sixth edition of the _Origin of Species_, Darwin attributed the origin of useless generic characters to useless specific characters; so that Mr. Wallace really gains nothing by his remark that specific characters are not specially mentioned in the present passage. Once more:-- "Darwin's latest expression of opinion on this question is interesting, since it shows he was inclined to return to his earlier view of the general, or universal, utility of specific characters[152]." [152] _Darwinism_, p. 142. This "latest expression of opinion," as I shall immediately prove, shows nothing of the kind--being, in fact, a mere re-statement of the opinion everywhere and at all times expressed by Darwin, touching the caution that must be observed in deciding, _with respect to individual cases_, whether an apparently useless specific character is to be regarded as really useless. Moreover, at no time and in no place did Darwin entertain any "view of the general, or universal, utility of specific characters." But the point now is, that if (as was the case) Darwin "inclined" to depart more and more from his earlier view of the highly _general_ utility of specific characters; and if (as was not the case) he ended by showing an inclination "_to return_" to this earlier view; what becomes of the whole of Mr. Wallace's contention against which this Appendix is directed, namely, _that Darwin never entertained any other view than that of the "general, or universal, utility of specific characters_"? The "latest expression of opinion" which Mr. Wallace quotes, occurs in a letter written to Professor Semper in 1878. It is as follows:--