ICOSANDRIA. 131 



in Europe, is conducted upon this principle, with a 

 full conviction of its importance j and with respect to 

 this favourite apple, in common with others, no atten- 

 tion has been paid to the situation where it is planted^ 

 a stiff clay, or a low and damp situation, are equally 

 uncongenial to its nature, but when placed in a dry or 

 loamy soil it returns to its former vigour, and accord- 

 ing to the season, its fruit is kind and of the same 

 goodness as before. 



The canker, so fatal a disease among trees, is no 

 indication of their decrepitude from old age ; it seems to 

 belong to some latent cause of which we are ignorant; 

 it is probably produced from the peculiar nature of 

 the soil, for, in many instances, I have traced it down 

 the albernum to the root. Young seedling trees of tlie 

 thorny and hardy crab, will often canker after put- 

 ting fortli strong and healthy shoots, for three or four 

 years, particularly if the situation be a wet and cold 

 clay.P 



P Another cause of the decay of fruit-trees is, that it is 

 customary to graft with wood less healthy than other branches 

 of the tree, because it is believed to produce fruit sooner than 

 younc;, kind, and vigorous shoots. 



Among timber trees the common Elm, Uhnus cawpestris, is 

 a good example of a tree that has been constantly produced by 

 grafts and suckers, which is at this day as healthy and fine a tree 

 as the same species at any former time, nor at all degenerated, 

 as we have any reason to believe ; while the VVych Elm, Ulmus 

 montana, which is constantly produced by seed, is still an inferior 



