[{299}] See Origin, Ed. i. p. 210, vi. p. 322, where the question is discussed for the case of instincts with a proviso that the same argument applies to structure. It is briefly stated in its general bearing in Origin, Ed. i. p. 87, vi. p. 106.
[{300}] «Note in original.» No one will dispute that the gliding is most useful, probably necessary for the species in question.
[{301}] «Note in original.» Is this the Galeopithecus? I forget. «Galeopithecus “or the flying Lemur” is mentioned in the corresponding discussion in the Origin, Ed. i. p. 181, vi. p. 217, as formerly placed among the bats. I do not know why it is described as partly aquatic in its habits.»
[{302}] In the Origin, Ed. vi. p. 221, the author modified the statement that it never climbs trees; he also inserted a sentence quoting Mr Hudson to the effect that in other districts this woodpecker climbs trees and bores holes. See Mr Darwin’s paper, Zoolog. Soc. Proc., 1870, and Life and Letters, iii. p. 153.
[{303}] Note by the late Alfred Newton. Richardson in Fauna Boreali-Americana, i. p. 49.
[{304}] «Note in original.» See Richardson a far better case of a polecat animal «Mustela vison», which half-year is aquatic. «Mentioned in Origin, Ed. i. p. 179, vi. p. 216.»
[{305}] In the Origin the division of the work into Parts I and II is omitted. In the MS. the chapters of Part II are numbered afresh, the present being Ch. I of Pt. II. I have thought it best to call it Ch. IV and there is evidence that Darwin had some thought of doing the same. It corresponds to Ch. IX of Origin, Ed. i., Ch. X in Ed. vi.
[{306}] In the Essay of 1842 the author uses astronomy in the same manner as an illustration. In the Origin this does not occur; the reference to the action of secondary causes is more general, e.g. Ed. i. p. 488, vi. p. 668.
[{307}] It is interesting to find the argument from sterility given so prominent a place. In a corresponding passage in the Origin, Ed. i. p. 480, vi. p. 659, it is more summarily treated. The author gives, as the chief bar to the acceptance of evolution, the fact that “we are always slow in admitting any great change of which we do not see the intermediate steps”; and goes on to quote Lyell on geological action. It will be remembered that the question of sterility remained a difficulty for Huxley.
[{308}] Similar statements occur in the Essay of 1842, p. 24, note 1, and in the Origin, Ed. i. p. 299.