APPENDIX. 703 



comparatively worthless, we believe that this is owing not to 

 natural limits set upon the duration of a variety ; that it does 

 not depend on the longevity of the parent tree ; but upon the 

 care with which the sort is propagated, and the nature of the 

 climate or soil where the tree is grown. 



It is a well established fact, that a seedling tree, if allowed to 

 grow on its own root, is always much longer lived, and often 

 more vigorous than the same variety, when grafted upon 

 another stock ; and experience has also proved that in propor- 

 tion to the likeness or close relation between the stock and the 

 graft is the long life of the grafted tree. Thus a variety of pear 

 grafted on a healthy pear seedling, lasts almost as long as upon 

 its own roots. Upon a thorn stock it does not endure so long. 

 Upon a mountain ash rather less. Upon a quince stock still 

 less ; until the average life of the pear tree when grafted on the 

 quince, is reduced from fifty years its ordinary duration on the 

 pear stock to about a dozen years. This is well known to 

 every practical gardener, and it arises from the want of affinity 

 between the quince stock and the pear graft. The latter is 

 rendered dwarf in its habits, bears very early, and perishes 

 equally soon. 



Next to this, the apparent decay of a variety is often caused 

 by grafting upon unhealthy stocks. For although grafts of very 

 vigorous habit have frequently the power of renovating in some 

 measure, or for a time, the health of the stock, yet the tree, 

 when it arrives at a bearing state, will, sooner or later, suffer 

 from the diseased or feeble nature of the stock. 



Carelessness in selecting scions for engrafting, is another 

 fertile source of degeneracy in varieties. Every good cultivator 

 is aware that if grafts are cut from the ends of old bearing 

 branches, exhausted by overbearing, the same feebleness of habit 

 will, in a great degree, be shared by the young graft. And on 

 the contrary, if the thrifty straight shoots that are thrown out 

 by the upright extremities, or the strong limb-sprouts, are 

 selected for grafting, they ensure vigorous growth, and healthy 

 habit in the graft. 



Finally, unfavourable soil and climate are powerful agents in 

 deteriorating varieties of fruit-trees. Certain sorts that have 

 originated in a cold climate, are often short-lived and unproduc- 

 tive when taken to warmer ones, and the reverse. This arises 

 from a want of constitutional fitness for a climate different from 

 its natural one. For this reason the Spitzenburgh apple soon 

 degenerates, if planted in the colder parts of New England, and 

 almost all northern sorts, if transplanted to Georgia. But this 

 only proves that it is impossible to pass certain natural limits 

 of fitness for climate, and not that the existence of the variety 

 itself is in any way affected by these local failures. 



Any or all of these causes are sufficient to explain the appa- 



