OF THE IMPKOVEMENT OF RACES. 807 



ance. There are, however, other points of great 

 importance on which the gardener has dependance. 



A fixed improvement in the quality of the produce 

 of a plant can only be obtained in one of two ways ; 

 either directly, by accidental variations in itself, or 

 indirectly, by the process of muling. 



Direct alterations in the quality of seedling plants 

 often occur from no apparent cause, just as those ao 

 cidental changes, called "sports," inthecolourorform 

 of the leaves, flowers, or fruit, of one single branch 

 of a tree, occasionally break out, we know not why. 

 Of these things, physiology can give no account ; but 

 it is known that, when those sports appear, they in- 

 dicate a permanent constitutional change in the action 

 of the limb thus affected, which changes may be 

 sometimes perpetuated by seed, and always by pro- 

 pagation of the limb itself, when propagation is prac- 

 ticable. It is in this way that many of our fruits have 

 probably, and several of the Chinese Chrysanthemums 

 have certainly, been obtained. It was apparently 

 thus that the Nectarine emanated from the Peach. It 

 is possible that many new forms of shrubs might be 

 procured ' by keeping these facts in view, and that 

 climbers might be deprived of their climbing habits ; 

 for it is known that the handsome evergreen bush 

 called the Tree Ivy, which grows erect, with scarcely 

 the least tendency to climb, has been procured by 

 propagating the fruit-bearing branches of trees of con- 

 siderable age. 



But we are by no means destitute of the power of 

 procuring, with considerable certainty, improved. 



