57 



external piths from external injury. Be- 

 sides the gnawing of horses, cattle like to 

 find soft-barked trees, such as Scotch firs, 

 &c., of a size that they can take between 

 their horns to rub their foreheads against, 

 and do infinite mischief in this way. Trees 

 that are too large for this are comparatively 

 safe, as the side rubbing of cattle does 

 .not injure them so much; besides, that 

 the dead epidermis of old trees is a great 

 defence to them. 



That the growth of the root is from the 

 descending sap seems clear from this, that 

 if the stem of a tree is rung at any part 

 between the root and the branches, so as 

 to intercept the sap returning from the 

 head, the tree will die, unless branches 

 shoot out below the ring, whose descend- 

 ing sap nourishes the root. 



In July 1832 I observed a horse-chesnut 

 tree near Esher, in the corner of a field 

 adjoining Sandown turnpike-gate. It had 



