VARIOUS THEORIES. 35 



a man. And all trees also which have been propagated from 

 such a seedling by means of buds or grafts, or, in other words, 

 all trees of the same variety, are to be considered as merely 

 extensions of that seedling, and will have a cotemporary 

 vigour and decline and decease with it. The period of vigour 

 or decline may be much extended by circumstances favour 

 able to the general health of any particular tree, and by un 

 favourable influences it may be shortened : but however well 

 situated, sooner or later it will manifest feebleness by the 

 change in the quality of its fruit, the small quantity it is able 

 to bear, by the decay of branches, and especially by its lia 

 bility to be attacked by diseases, such as the canker, which 

 rapidly destroy its remaining vitality. These diseases may 

 be guarded against, and may often be cured ; but the longer 

 the period since the origin of the variety from a seed, the 

 greater the liability and the more difficult the cure.* 



This theory is entirely discredited by other distinguished 

 botanists and horticulturists, among whom are Dr. Lindley in 

 England, Decandolle on the Continent, and Mr. Downing and 

 H. W. Beecher in America. 



These consider that there is no such similarity between the 

 life of a tree and the life of an animal, and that a bud and a 

 seed contain equally the germ of new life, that they are, in 

 fact, the same thing, except that they are prepared to be 

 developed under different circumstances. That each bud, 

 twig, and branch, has a life of its own, and the trunk is but an 

 association of roots, or of connections between each bud and its 



* Professor Turner, of Illinois College, advocates the view that every 

 time a seedling tree is divided, whether in root or top, its natural longevity 

 and proportionate vital force are proportionally divided, abstracted, and 

 shortened ; and believes that some of the worst forms of hereditary, and 

 also of annual diseases, flow from a succession of such mutilations through 

 a series of generations, or are produced by an effort of nature to resist and 

 repair this interference with her natural processes. 



