[{290}] «Note in original.» Macculloch and others.
[{291}] I can find no reference to the transandantes sheep in Darwin’s published work. He was possibly led to doubt the accuracy of the statement on which he relied. For the case of the sheep returning to their birth-place see [p. 17, note 4].
[{292}] Origin, Ed. i. p. 224, vi. p. 342.
[{293}] This is an expansion of an obscure passage in the Essay of 1842, p. [19].
[{294}] The difficulties discussed in the Origin, Ed. i. p. 171, vi. p. 207, are the rarity of transitional varieties, the origin of the tail of the giraffe; the otter-like polecat (Mustela vison); the flying habit of the bat; the penguin and the logger-headed duck; flying fish; the whale-like habit of the bear; the woodpecker; diving petrels; the eye; the swimming bladder; Cirripedes; neuter insects; electric organs.
Of these, the polecat, the bat, the woodpecker, the eye, the swimming bladder are discussed in the present Essay, and in addition some botanical problems.
[{295}] In the Origin, Ed. vi. p. 275, the author replies to Mivart’s criticisms (Genesis of Species, 1871), referring especially to that writer’s objection “that natural selection is incompetent to account for the incipient stages of useful structures.”
[{296}] «The following sentence seems to have been intended for insertion here» “and that each eye throughout the animal kingdom is not only most useful, but perfect for its possessor.”
[{297}] Origin, Ed. i. p. 190, vi. p. 230.
[{298}] This is one of the most definite statements in the present Essay of the possible importance of sports or what would now be called mutations. As is well known the author afterwards doubted whether species could arise in this way. See Origin, Ed. v. p. 103, vi. p. 110, also Life and Letters, vol. iii. p. 107.