DURATION OF VARIETIES. 558 



with which the sort is propagated, and the nature of the cli- 

 mate 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 

 grait is the long life of the grafted tree. Thus a variety of 

 pear grafted on a healtny 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 dura- 

 lion 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 per- 

 ishes 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 cultiva- 

 tor 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 

 apparent decay of some varieties of fruit, and especially of 

 pears, over which some cultivators, of late, have uttered so 



