CH. VI, 9] METHODS OF PLANT BREEDING 319 



cation of variations must sometime and somehow occur, else 

 we could never have obtained our multiform and multi- 

 chrome Chrysanthemums from their comparatively uniform 

 and simple wild ancestors '; and the variation once intensified, 

 by whatever method, could be isolated to a variety by se- 

 lection. This method of improvement by selection is slow, 

 but is favored by use of great numbers of plants, and by the 

 fact that plants vary more rapidly and extremely under 

 cultivation than in the wild state. In this indirect way, 

 indeed, cultivation does promote the development of new 

 varieties. 



2. The preservation of sports. Occasionally some one bud 

 on a plant will produce a branch having leaves, flowers, or 

 fruits strikingly different from those on the rest of the plant, 

 such a feature being called a SPORT. If, now, that particular 

 branch be propagated by cuttings or by grafting, the new 

 feature holds true; and thus the plants which contain 

 it can be multiplied indefinitely. The Red, or Copper, 

 Beeches, familiar lawn trees, originated in a single red- 

 leaved branch on an ordinary Green Beech, and have 

 since been propagated and multiplied by grafting. The 

 Navel Orange, which is seedless, and further distinguished 

 by the small accessory Orange within its upper end 

 (page 201), originated in a sport branch upon an ordinary 

 Orange tree, and has been preserved and spread by bud- 

 ding (a form of grafting). Indeed, most highly developed 

 fruits have originated thus; somebody has found them as 

 sports upon more ordinary kinds, and preserved them by 

 grafting. If the sporting branch cannot be propagated by 

 cuttings or by grafting, the sport cannot be preserved at 

 all, for bud sports are not reproduced by their seeds, which 

 produce only the original form. Sometimes, however, 

 SEED SPORTS appear, in which case the sports come true to 

 seed and can thus be propagated, as in case of some fruit 

 trees and a few garden herbs. 



The mode and causes of origin of sports are unknown. 



