8 THE ORIGIN OF SPECIES 



stand domestication or cultivation, and vary very slightly — per- 

 haps hardly more than in a state of nature. 



Some naturalists have maintained that all variations are con- 

 nected with the act of sexual reproduction; but this is certainly an 

 error; for I have given in another work a long list of "sporting 

 plants," as they are called by gardeners; that is, of plants which 

 have suddenly produced a single bud with a new and sometimes 

 widely different character from that of the other buds on the same 

 plant. These bud variations, as they may be named, can be propa- 

 gated by grafts, offsets, etc., and sometimes by seed. They occur 

 rarely under nature, but are far from rare under culture. As a 

 single bud out of 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 conditions, 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 conditions is of subordinate im- 

 portance in comparison with the nature of the organism in deter- 

 mining each particular form of variation; perhaps of not more 

 importance than the nature of the spark, by which a mass of com- 

 bustible matter is ignited, has in determining 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 an- 

 other. 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 pro- 

 portion 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 and 

 goats in countries where they are habitually milked, in comparison 

 with these organs in other countries, is probably another instance 

 of the effects of use. Not one of our domestic animals can be named 

 which has not in some country drooping ears; and the view which 

 has been suggested that the drooping is due to disuse of the 

 muscles of the ear, from the animals being seldom much alarmed, 

 seems probable. 



Many laws regulate variation, some few of which can be dimly 



