[95] _Origin of Species_, p. 176: italics mine, as also in the following. Elsewhere we read:-- "Each of the endless variations which we see in the plumage of our fowls must have had some efficient cause; and if the _same_ cause were to act _uniformly_ during a long series of generations on _many_ individuals, _all_ probably would be modified in the same manner." As special illustrations of this fact I may quote the following cases from Darwin's works. "Dr. Bachman states that he has seen turkeys raised from the eggs of wild species, lose their metallic tints, and become spotted in the third generation. Mr. Yarrell many years ago informed me that the wild ducks bred in St James' Park lost their true plumage after a few generations. An excellent observer (Mr. Hewitt) ... found that he could not breed wild ducks true for more than five or six generations, as they proved so much less beautiful. The white collar round the neck of the mallard became broader and more irregular, and white feathers appeared in the duckling's wings &c.[96]" [96] _Var._ vol. ii. p. 250. Now, such cases--to which numberless others might be added--prove that even the subtle and inconspicuous causes incidental to domestication are capable of inducing changes of specific character quite as great, and quite as "stable," as any that in a state of nature are taken to constitute specific distinctions. Yet there can here be no suggestion of utility, inasmuch as the change takes place in the course of a few generations, and therefore without leaving time for natural selection to come into play--even if it ever could come into play among the sundry domesticated birds in question. But the facts of domestication also make for the same conclusion in another way--namely, by proving that when time enough _has_ been allowed for the production of useless changes of greater magnitude, such changes are not infrequently produced. And the value of this line of evidence is that, great as are the changes, it is impossible that either natural or artificial selection can have been concerned in their production. It will be sufficient to give two examples--both with regard to structure. The first I will render in the words whereby it has already been stated in my own paper on _Physiological Selection_, because I should like to take this opportunity of answering Mr. Wallace's objection to it.