262 



CAUSES OF VAEIABILITY. 



Chap. XXII. 



same general effect. Mr. Salter 26 remarks, " Every one knows 



" that the chief difficulty is in breaking through the original form 

 " and colour of the species, and every one will be on the look-out 

 " for any natural sport, either from seed or branch ; that bein 

 " once obtained, however trifling the change may be, the result 



<y 



a 



" depends upon himself." M. de Jonghe, who has had so much 

 success in raising new varieties of pears and strawberries, 27 re- 

 marks with respect to the former, " There is another principle, 

 " namely, that the more a type has entered into a state of variation, 

 the greater is its tendency to continue doing so ; and the more 

 " it has varied from the original type, the 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 augmenting in the same direc- 

 tion each modification; for this power depends on continued 

 variability of the same general kind. The most celebrated hor- 

 ticulturist in France, namely, Vilmorin, 28 even maintains that, 

 when any particular variation is desired, the first step is to 



;et 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 be- 

 lieved, with domestic ducks, lost their true plumage after a 

 few generations. An excellent observer, 30 who has often reared 

 birds from the eggs of the wild duck, and who took precautions 



&<$., 1865, p. 28. 



29 * Examination of the Characteris- 



26 « The Chrysanthemum, its History, 



&c.,' 1865, p. 3. 



27 • Gardener's Chron,,' 1855, p. 54 ; tics of Genera and Species :' Charleston, 



• Journal of Horticulture,' May 9* 1865, 1855, p. 14. 

 p. 363. 



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



' 



28 Quoted by Verlot, ' Des Varietes/ 1863, p. 39. 



