LETTER X. 



101 



individual plant, and is endowed with Yitality in its 

 every part. On this supposition, such a change 

 occurring in the heart-wood should spread, or might 

 reasonably be expected to extend to the adjoining 

 living parts, and, sooner or later, but before very 

 long, to kill the whole tree. This, however, does not 

 happen ; nor is the complete and premature decay 

 of an entire tree ever due to the agency of such a 

 cause. 



9. It has thus, I hope, in this and the two preceding 

 Letters, been satisfactorily made out — first, That the 

 growths emanating from the huds of trees constitute 

 severally perfect and independent plants ; and, secondly, 

 That what remains of them, after the fall of the leaves, 

 and flowers, and fruit, with the single exception of the 

 buds, ceases to live, and never afterwards becomes the 

 seat of any vital action. 



10. And if this be conceded, it will probably be 

 allowed also, that the view here presented of the 

 nature and of the natural longevity and size of trees 

 is well-founded ; — that is to say, that a tree is simply 

 a corporation sole " — a collection, aggregate, or 

 congregation of annual plants of the same species, the 

 production of a series of successive years, the indi- 

 vidual plants of each year shooting up in spring from 

 buds adherent to the persistent dead remains of the 

 plants of the previous year, growing as parasites on 

 these remains, putting on the character of old age in 



