352 EFFECTS OF STOCKS 



a slow-growing bush or small tree, the Pear is a large forest- 

 tree of rapid growth; and the Pear will grow an inch in 

 diameter while the Hawthorn is growing half an inch. 

 Moreover all the qualities of the Pear are different from those 

 of the Hawthorn. 



The difference in the rate of growth or in other respects, if 

 not excessive, may be taken advantage of for particular 

 purposes. When 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 explanation of trees dwarfed by being 

 compelled to grow upon a stock which compels their descend- 

 ing sap to accumulate in the branches has been already given. 

 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 Graftiag," published in the Horticultwal 

 Transactions, ii. 199. 



"The disposition in young trees to produce and nourish 

 blossom-buds and fruit is increased by this apparent obstruc' 

 tion of the descending sap ; and the fruit of such young trees 

 ripens, I think, somewhat earlier that 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 dimiaished, apparently, by the 

 stagnation, in the branches and stock, of a portion of that sap 

 which, in a tree growing upon its own stem, or upon a stock of 

 its own species, would descend 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 eligible whereyer it is wished to diminish the 

 vigour and growth of the tree, and where its durability is not 

 thought important. 



"When," adds this great gardener, "much difficulty is found 

 in making a tree, whether fructiferous or ornamental, of any 



