1 2 VARIATION UNDER DOMESTICATION. [Chap. I. 



on the same plant. These bud variations, as they may 

 be named, can be propagated by grafts, offsets, &c, and 

 sometimes by seed. They occur rarely under nature, 

 but are far from rare under culture. As a single bud 

 out of the many thousands, produced year after year on . 

 the same tree under uniform conditions, has been 

 known suddenly to assume a new character ; and as 

 buds on distinct trees, growing under different con- 

 ditions, have sometimes yielded nearly the same variety 

 — for instance, buds on peach-trees producing nec- 

 tarines, and buds on common roses producing moss- 

 roses — we clearly see that the nature of the con- 

 ditions is of subordinate importance in comparison 

 with the nature of the organism in determining each 

 particular form of variation ; — perhaps of not more 

 importance than the nature of the spark, by which a 

 mass of combustible matter is ignited, has in deter- 

 mining the nature of the flames. 



Effects of Habit and of the Use or Disuse of Parts; 

 Correlated Variation ; Inheritance. 



Changed habits produce an inherited effect, as in the 

 period of the flowering of plants when transported from 

 one climate to another. With animals the increased 

 use or disuse of parts has had a more marked influence ; 

 thus I find in the domestic duck that the bones of the 

 wing weigh less and the bones of the leg more, in 

 proportion to the whole skeleton, than do the same 

 bones in the wild-duck ; and this change may be 

 safely attributed to the domestic duck flying much 

 less, and walking more, than its wild parents. The 

 great and inherited development of the udders in cows 



