The words “several years ago, and” seem to have been added at a later date.
35
Life and Letters, ii. p. 9.
36
Evidently a memorandum that an example should be given.
37
The importance of exposure to new conditions for several generations is insisted on in the Origin, Ed. i. p. 7, also p. 131. In the latter passage the author guards himself against the assumption that variations are “due to chance,” and speaks of “our ignorance of the cause of each particular variation.” These statements are not always remembered by his critics.
38
Cf. Origin, Ed. i. p. 10, vi. p. 9, “Young of the same litter, sometimes differ considerably from each other, though both the young and the parents, as Müller has remarked, have apparently been exposed to exactly the same conditions of life.”
39
This is paralleled by the conclusion in the Origin, Ed. i. p. 8, that “the most frequent cause of variability may be attributed to the male and female reproductive elements having been affected prior to the act of conception.”
40
The meaning seems to be that there must be some variability in the liver otherwise anatomists would not speak of the ‘beau ideal’ of that organ.
41
The position of the following passage is uncertain. “If individuals of two widely different varieties be allowed to cross, a third race will be formed – a most fertile source of the variation in domesticated animals. «In the Origin, Ed. i. p. 20 the author says that “the possibility of making distinct races by crossing has been greatly exaggerated.”» If freely allowed, the characters of pure parents will be lost, number of races thus «illegible» but differences «?» besides the «illegible». But if varieties differing in very slight respects be allowed to cross, such small variation will be destroyed, at least to our senses, – a variation [clearly] just to be distinguished by long legs will have offspring not to be so distinguished. Free crossing great agent in producing uniformity in any breed. Introduce tendency to revert to parent form.”
42
The swamping effect of intercrossing is referred to in the Origin, Ed. i. p. 103, vi. p. 126.
43
A discussion on the intercrossing of hermaphrodites in relation to Knight’s views occurs in the Origin, Ed. i. p. 96, vi. p. 119. The parallelism between crossing and changed conditions is briefly given in the Origin, Ed. i. p. 267, vi. p. 391, and was finally investigated in The Effects of Cross and Self-Fertilisation in the Vegetable Kingdom, 1876.
44
There is an article on the vis medicatrix in Brougham’s Dissertations, 1839, a copy of which is in the author’s library.
45
This is the classification of selection into methodical and unconscious given in the Origin, Ed. i. p. 33, vi. p. 38.
46
This passage, and a similar discussion on the power of the Creator (p. 6), correspond to the comparison between the selective capacities of man and nature, in the Origin, Ed. i. p. 83, vi. p. 102.
47
i. e. they are individually distinguishable.
48
See Origin, Ed. i. p. 133, vi. p. 165.
49
When the author wrote this sketch he seems not to have been so fully convinced of the general occurrence of variation in nature as he afterwards became. The above passage in the text possibly suggests that at this time he laid more stress on sports or mutations than was afterwards the case.
50
The author may possibly have taken the case of the woodpecker from Buffon, Histoire Nat. des Oiseaux, T. vii. p. 3, 1780, where however it is treated from a different point of view. He uses it more than once, see for instance Origin, Ed. i. pp. 3, 60, 184, vi. pp. 3, 76, 220. The passage in the text corresponds with a discussion on the woodpecker and the mistletoe in Origin, Ed. i. p. 3, vi. p. 3.
51
This illustration occurs in the Origin, Ed. i. pp. 90, 91, vi. pp. 110, 111.
52
See Origin, Ed. i. p. 83, vi. p. 102, where the word Creator is replaced by Nature.
53
Note in the original. “Good place to introduce, saying reasons hereafter to be given, how far I extend theory, say to all mammalia – reasons growing weaker and weaker.”
54
See Origin, Ed. i. pp. 62, 63, vi. p. 77, where similar reference is made to De Candolle; for Malthus see Origin, p. 5.
55
This may possibly refer to the amount of destruction going on. See Origin, Ed. i. p. 68, vi. p. 84, where there is an estimate of a later date as to death-rate of birds in winter. “Calculate robins” probably refers to a calculation of the rate of increase of birds under favourable conditions.
56
In the Origin, Ed. i. pp. 64, 65, vi. p. 80, he instances cattle and horses and certain plants in S. America and American species of plants in India, and further on, as unexpected effects of changed conditions, the enclosure of a heath, and the relation between the fertilisation of clover and the presence of cats (Origin, Ed. i. p. 74, vi. p. 91).
57
Origin, Ed. i. p. 74, vi. p. 91. “It has been observed that the trees now growing on … ancient Indian mounds … display the same beautiful diversity and proportion of kinds as in the surrounding virgin forests.”
58
The simile of the wedge occurs in the Origin, Ed. i. p. 67; it is deleted in Darwin’s copy of the first edition: it does not occur in Ed. vi.
59
In a rough summary at the close of the Essay, occur the words: – “Every creature lives by a struggle, smallest grain in balance must tell.”
60
Cf. Origin, Ed. i. p. 77, vi. p. 94.
61
This is a repetition of what is given at p. 6.
62
Compare Origin, Ed. i. p. 41, vi. p. 47. “I have seen it gravely remarked, that it was most fortunate that the strawberry began to vary just when gardeners began to attend closely to this plant. No doubt the strawberry had always varied since it was cultivated, but the slight varieties had been neglected.”
63
Here we have the two types of sexual selection discussed in the Origin, Ed. i. pp. 88 et seq., vi. pp. 108 et seq.
64
It is not obvious why the author objects to “chance” or “external conditions making a woodpecker.” He allows that variation is ultimately referable to conditions and that the nature of the connexion is unknown, i.e. that the result is fortuitous. It is not clear in the original to how much of the passage the two? refer.
65
The meaning is “That sterility is not universal is admitted by all.”
66
See Var. under Dom., Ed. 2, i. p. 388, where the garden forms of Gladiolus and Calceolaria are said to be derived from crosses between distinct species. Herbert’s hybrid Crinums are discussed in the Origin, Ed. i. p. 250, vi. p. 370. It is well known that the author believed in a multiple origin of domestic dogs.
67
The argument from gradation in sterility is given in the Origin, Ed. i. pp. 248, 255, vi. pp. 368, 375. In the Origin, I have not come across the cases mentioned, viz. crocus, heath, or grouse
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