[170] ‘Die Taubenzucht,’ 1824, s. 86.
[171] ‘Ornithological Biography,’ vol. i. p. 13.
[172] ‘Proc. Zool. Soc.’ 1835, p. 54. The japanned peacock is considered by Mr. Sclater as a distinct species, and has been named Pavo nigripennis.
[173] Rudolphi, ‘Beyträge zur Anthropologie,’ 1812, s. 184.
[174] ‘Die Darwin’sche Theorie, und ihre Stellung zu Moral und Religion,’ 1869, s. 59.
[175] In regard to peafowl, see Sir R. Heron, ‘Proc. Zoolog. Soc.’ 1835, p. 54, and the Rev. E. S. Dixon, ‘Ornamental Poultry,’ 1848, p. 8. For the turkey, Audubon, ibid. p. 4. For the capercailzie, Lloyd, 'Game Birds of Sweden,’ 1867, p. 23.
[176] Mr. Hewitt, quoted in ‘Tegetmeier’s Poultry Book,’ 1866, p. 165.
[177] Quoted in Lloyd’s ‘Game Birds of Sweden,’ p. 345.
[178] According to Dr. Blasius (‘Ibis,’ vol. ii. 1860, p. 297), there are 425 indubitable species of birds which breed in Europe, besides 60 forms, which are frequently regarded as distinct species. Of the latter, Blasius thinks that only ten are really doubtful, and that the other fifty ought to be united with their nearest allies; but this shews that there must be a considerable amount of variation with some of our European birds. It is also an unsettled point with naturalists, whether several North American birds ought to be ranked as specifically distinct from the corresponding European species.
[179] ‘Origin of Species,’ fifth edit. 1869, p. 104. I had always perceived, that rare and strongly-marked deviations of structure, deserving to be called monstrosities, could seldom be preserved through natural selection, and that the preservation of even highly-beneficial variations would depend to a certain extent on chance. I had also fully appreciated the importance of mere individual differences, and this led me to insist so strongly on the importance of that unconscious form of selection by man, which follows from the preservation of the most valued individuals of each breed, without any intention on his part to modify the characters of the breed. But until I read an able article in the ‘North British Review’ (March, 1867, p. 289, et seq.), which has been of more use to me than any other Review, I did not see how great the chances were against the preservation of variations, whether slight or strongly pronounced, occurring only in single individuals.