32 



on a plum stock, &c., the new growth in 

 diameter on the stock is still plum, which 

 it would not be if the new crrowth was 

 entirely derived from the peach leaves, or 

 even if it was entirely elaborated in them, 

 and entirely deposited from the downward 

 sap ; while, on the other hand, if the 

 elaboration was wholly in the root or 

 lower stem the wood and leaves of the 

 peach would become plum. But purple 

 beech and variegated sycamore grow for 

 ever unchano;ed, thouo:h eno^rafted on com- 

 mon stocks, as a single branch of a plant 

 accidentally variegated will for ever retain 

 its character. This looks like local elabo- 

 ration. 



I think it possible that engrafting trees 

 on stocks of minor growth may incline 

 them to fruit instead of growth, on the 

 same principle as ringing branches or tying 

 ligatures round them does. In each case 

 the natural supply of sap is diminished. 



The upward growth of a tree, as com- 



