Now, in the first place; this is not the interpretation adopted by Darwin. For instance, he expressly contrasts such cases with those of vestigial or "rudimentary" structures, pointing out that they differ from vestigial structures in respect of their permanence. One quotation will be sufficient to establish the present point. "A structure which has been developed through long-continued selection, when it ceases to be of service to a species, generally becomes variable, as we see with rudimentary organs, for it will no longer be regulated by this same power of selection. But when, from the nature of the organism and of the conditions, modifications have been induced which are unimportant for the welfare of the species, they may be, and apparently often have been, transmitted in nearly the same state to numerous, otherwise modified, descendants[130]." [130] _Origin of Species_, p. 175. Here, and in the context, we have a sufficiently clear statement of Darwin's view--first, that unadaptive characters may arise in _species_ as "fluctuating variations, which sooner or later become _constant_ through the nature of the organism and of surrounding conditions, as well as through the intercrossing of distinct individuals, but _not_ through natural selection"[131]; second, that such unadaptive characters may then be transmitted in this their stable condition to species-progeny, so as to become distinctive of genera, families, &c.; third, that, on account of such characters not being afterwards liable to diverse adaptive modifications in different branches of the species-progeny, they are of more value as indicating lines of pedigree than are characters which from the first have been useful; and, lastly, they are therefore now empirically recognized by systematists as of most value in guiding the work of classification. To me it appears that this view is not only perfectly rational in itself, but likewise fully compatible with the theory of natural selection--which, as I have previously shown, is _primarily_ a theory of adaptive characters, and therefore not necessarily a theory of _all_ specific characters. But to those who think otherwise, it must appear--and does appear--that there is something wrong about such a view of the case--that it was not consistent in the author of the _Origin of Species_ thus to refer non-adaptive generic characters to a parentage of non-adaptive specific characters. Nevertheless, as a matter of fact, Darwin was perfectly consistent in putting forth this view, because, unlike Wallace, he was not under the sway of any antecedent dogma erroneously deduced from the theory of natural selection. [131] _Ibid._ p. 176: italics mine.