246 PROPAGATION OF PLANTS. 



on the graft. It mainly affects the form and habit of 

 growth, but is not necessarily debilitating, for size and 

 rapid growth are not always trustworthy signs of perfect 

 health or great longevity. 



In some instances we employ stocks as a mere tem- 

 porary support to the cion, not expecting or desiring a 

 permanent union, as in grafting the tree Pseonia 

 upon the tuber of the herbaceous, or the stem of one 

 Dahlia upon the tuber of another. But with trees we 

 usually seek permanency, and therefore select stocks that 

 shall not only support the graft, but aid in developing 

 those particular characteristics which are most desired. 

 The influence of the stock upon the graft may be briefly 

 stated as follows : 



First, The stock gathers the crude materials for the 

 support of the graft from the soil, and in doing so it 

 may supply it in such quantities as to produce rapid 

 growth, or the reverse. 



Second, The tendency of the' stock is to impart its own 

 habit of growth to the graft. 



Third, One species of stock will extract from the soil 

 the peculiar components which are necessary to support 

 the graft, while another will not ; consequently, a variety 

 or species may fail upon one stock and succeed upon 

 another in the same soil and locality. 



Fourth, The hardiness of a tree is but slightly changed 

 or affected by the stock, except as its growth is influenced 

 to mature early or late in the season. 



Fifth, The quality of a fruit is occasionally in- 

 fluenced by the stock, but the true cause of this is not as 

 yet sufficiently understood to allow of any rules being 

 given by which it may be avoided. Size of fruit is also 

 in some instances considerably changed by the use of dif- 

 ferent stocks. I have known two Bartlett Pear trees of 

 the same age, standing side by side, and apparently of 

 equal vigor, still, for ten years, one has produced very 



