250 CAUSES OF VAKI ABILITY. Chap. XXII 



" more it is disposed to vary still farther." We have, indeed, 

 already discussed this latter point when treating of the power 

 which man possesses, through selection, of continually aug- 

 menting in the same direction each modification; for this 

 power depends on continued variability of the same general 

 kind. The most celebrated horticulturist in France, namely, 

 Vilmorin, 28 even maintains that, when any particular varia- 

 tion is desired, the first step is to get the plant to vary in 

 any manner whatever, and to go on selecting the most 

 variable individuals, even though they vary in the wrong 

 direction; for the fixed character of the species being once 

 broken, the desired variation will sooner or later appear. 



As nearly all our animals were domesticated at an extremely 

 remote epoch, we cannot, of course, say whether they varied 

 quickly or slowly when first subjected to new conditions. 

 But Dr. Bachman 29 states that he has seen turkeys raised 

 from the eggs of the wild species lose their metallic tints and 

 become spotted with white in the third generation. Mr. 

 Yarrell many years ago informed me that the wild ducks 

 bred on the ponds in St. James's Park, which had never been 

 crossed, as it is believed, with domestic ducks, lost their true 

 plumage after a few generations. An excellent observer, 30 

 who has often reared ducks from the eggs of the wild bird, 

 and who took precautions that there should be no crossing 

 with domestic breeds, has given, as previously stated, full 

 details on the changes which they gradually undergo. He 

 found that he could not breed these wild ducks true for more 

 than five or six generations, "as they then proved so much 

 " less beautiful. The white collar round the neck of the 

 k ' mallard became much broader and more irregular, and 

 " white feathers appeared in the ducklings' wings." They 

 increased also in size of body; their legs became less fine, 

 and they lost their elegant carriage. Fresh eggs were then 

 procured from wild birds ; but again the same result followed. 

 In these cases of the duck and turkey we see that animals, 



2S Quoted bv Verlot, • Des Yarietes,' ton, 1855, p. 14. 

 & ,18 . 30 Mr. Hewitt, 'Journal of Hort , 



- 9 ' Examination of the Characteris- 1863, p. 39. 

 tics of Genera and Species :' Charles- 



