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if a seedling apple-tree is cut into two parts, and these parts are 

 reunited by grafting, the duration of the tree will be shorter than it 

 would have been in the absence of the operation. 



" It is nevertheless believed by many that the races of some culti- 

 vated plants have but a brief duration, provided they are multiplied 

 otherwise than by seeds. No one indeed pretends that the garlic of 

 Ascalon has only a short life, although it has been thus propagated 

 from the time when it bore the name of Shummin, and fed the 

 labourers at the Pyramids ; nor do we know that the bulb-bearing lily 

 has been supposed to have less inherent vigour than if it were mul- 

 tiplied by seeds insteads of bulbs. It is only among certain kinds of 

 plants that exceptions to the great natural law of vegetation are sup- 

 posed to exist. It is thought that although the wild potato possesses 

 indefinite vitality, yet that the varieties of it which are brought 

 into cultivation pass their lives circumscribed within very narrow 

 limits ; and the same doctrine has been held concerning fruit-trees. 

 The great advocate of this view, the late Mr. Andrew Knight, rested 

 his case upon the disappearance of certain kinds of apples and pears, 

 once to be found in the orchards of Herefordshire, but now no longer 

 to be met with. This he ascribed to cultivated varieties being natu- 

 rally short-lived, and to an impossibility of arresting their gradual de- 

 cay by any process of dismemberment ; and following out this theory 

 he strongly urged the necessity of renewing vitality by continually 

 raising fresh varieties from seed. It is difficult to comprehend what 

 train of reasoning led to this speculation. We know that wild plants 

 may be propagated by dismemberment for an indefinite period ; we 

 know that when such wild plants spring up from seed the dismember- 

 ing process still goes on and still without exhibiting symptoms of 

 exhausted vitality ; and yet if a plant grows in a garden, and is 

 brought under the direct control of man, the power is thought to be 

 lost, or so much impaired that indefinite multiplication no longer 

 becomes possible. Can this be true ? Most assuredly the cases 

 adduced in support of the doctrine are susceptible of another expla- 

 nation, perfectly consistent with the general laws of vegetation. 



" That renewal by seed will not restore what is called exhausted 

 vitality, was sufficiently proved by the experiments with potatoes 

 after the blight made its appearance. We were assured by an inge- 

 nious writer in one of the daily papers that the constitutional power 

 of the potato was on the decline ; in other words, that the lives of 

 individuals was approaching their end ; that the blight arose in conse- 

 quence, and that a certain remedy would be the renewal of the exist- 



