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Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: the last edition of The Origin of Species was prepared; and it is clear that Mr. Darwin himself did not fully recognise the enormous amount of variability that actually exists. This isv indicated by his frequent reference to the extreme slowness of the changes for which variation furnishes the materials, and also by his use of such expressions as the following: "A variety when once formed must again, perhaps after a long interval of time, vary or present individual differences of the same favourable nature as before" (Origin, p. 66). And again, after speaking of changed conditions " affording a better chance of the occurrence of favourable variations," he adds: " Unless such occur natural selection can do nothing" (Origin, p. 64). These expressions are hardly consistent with the fact of the constant and large amount of variation, of every part, in all directions, which evidently occurs in each generation of all the more abundant species, and which must afford an ample supply of favourable variations whenever required; and they have been seized upon and exaggerated by some writers as proofs of the extreme difficulties in the way of the theory. It is to show that such difficulties do not exist, and in the full conviction that an adequate knowledge of the facts of variation affords the only sure foundation for the Darwinian theory of the origin of species, that this chapter has been written. CHAPTER IV VARIATION OF DOMESTICATED ANIMALS AND CULTIVATED PLANTS The facts of variation and artificial selectionProofs of the generality of variationVariations of apples and melonsVariations of flowers Variations of domestic animalsDomestic pigeonsAcclimatisation Circumstances favourable to selection by manConditions favourable to variationConcluding remarks. Having so fu...
| ISBN-13 | 9781459066090 |
|---|---|
| ISBN-10 | 145906609X |
| Weight | 1.24 Pounds |
| Dimensions | 9.00 x 6.00 x 0.85 In |
| List Price | $17.86 |
| Format | Paperback |
|---|---|
| Pages | 382 pages |
| Publisher | |
| Published On | 2009-08-01 |
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