OF PROPAGATION BY GRAFTING. 227 



trees grow too large for a small garden, it is desirable 

 to dwarf them; and when they are naturally unfruit- 

 ful, to render them productive: both which effects 

 result, at the same time, from grafting them upon 

 stocks that grow slower than themselves. Thus the 

 Apple is dwarfed by grafting on the Paradise stock, 

 and the Pear by the Quince. The physiological ex- 

 planation of trees dwarfed by being compelled to 

 grow upon a stock which compels their descending 

 sap to accumulate in the branches has been already 

 given (85). Instead of repeating it here, I take the 

 following paragraph from the paper by Mr. Knight, 

 " On the Effects of Different Kinds of Stocks in Graft- 

 ing," published in the HoriicuUural Transactions, ii. 

 199. 



"The disposition in young trees to produce and 

 nourish blossom buds and fruit is increased by this 

 apparent obstruction of the descending sap ; and the 

 fruit of such young trees ripens, I think, somewhat 

 earlier than upon other young trees of the same age, 

 which grow upon stocks of their own species ; but 

 the growth and vigour of the tree, and its power to 

 nourish a succession of heavy crops, are diminished, 

 apparently, by the stagnation, in the branches and 

 stock, of a portion of that sap which, in a tree grow- 

 ing upon its own stem, or upon a stock of its own 

 species, would descetid to nourish and promote the 

 extension of the roots. The practice, therefore, of 

 grafting the Pear tree on the Quince stock, and the 

 Peach and Apricot on the Plum, where extensive 

 growth and durability are wanted, is wrong ; but it is 



