MUTUAL INFLUENCE OF THE STOCK AND GRAFT. 147 



probably due to the trees having rooted from the graft. The observed 

 changes in the form of the fruit of the graft, causing it to resemble that 

 of the stock, are as yet too few to be considered other than accidental. 



3. Fruitfulness. — The most important of all the results of grafting is 

 increased fruitfulness. This is brought about (a) by the mere process ©f 

 grafting, which operates in the same manner as a ligature, or the removal 

 of a ring of bark; (6) by diminished vigor through defective nourishment 

 from a feebler stock; (c) by increased vigor imparted by vigorous 

 stocks to varieties which are naturally too feeble to bear heavily. 



4. Precocity. — Earlier, as well as more abundant, fruiting is induced 

 by the act of grafting; also by diminished vigor due to dwarf or feeble 

 stocks. The precocity of trees on dwarf stocks is not, however, always 

 directly due to diminished vigor, but largely to the habit of early bearing 

 imparted to the graft by the stock in a manner not fully understood. 

 Probably the diminished supply of sap derived from dwarf or feeble stocks, 

 and its consequent richer character, is an important factor in inducing 

 the earlier and more abundant fruitfulness. 



5. Season of growth and maturity. — The stock and the graft each mod- 

 ifies the period of vegetation of the other when their normal times of 

 beginning or closing their season's growth are different. Thus, a late 

 variety grafted upon an early stock begins and ends its season's growth 

 earlier than it otherwise would. This alteration in habit appears in some 

 cases to affect the time of ripening of the fruit. 



6. Hardiness. — There is some evidence that hardy stocks increase the 

 hardiness of the grafts. This, however, does not appear to be by the trans- 

 fer of any inherent hardiness peculiar to the variety, but to result from 

 the increased or diminished vigor in certain cases or an earlier maturity 

 in varieties which, upon their own roots, are inclined to grow too late in 

 the season. The advantage usually sought in hardy stocks is to furnish 

 hardy stems able to resist injury to the bark by sun-scald, etc., and to sup- 

 ply roots of uniform hardiness in place of those of ordinary seedlings 

 which are frequently less hardy than those of most cultivated varieties. 

 Conversely, a hardy graft has been known to increase the hardiness of the 

 stock, but known examples of this are rare, and usually no such influence 

 can be observed. 



7. Adaptation to soil. — " Favored by the influence of the stock, many 

 species are able to thrive in unfavorable soils, and often in those in which 

 they could not live if upon their own roots." There is in this fact no evi- 

 dence that the character of either stock or graft is modified. In some 

 cases, however, the demands of a vigorous or fruitful graft may render the 

 roots of the stock more exacting as to soil, so that they require one which 

 is more fertile or of more definite character in which to maintain in health 

 the grafted tree than would be required for a tree of the same kind as the 

 stock growing in its natural state. 



8. Color. — An alteration in color, as the result of grafting, may occur 

 (a), by the direct transfer of coloring matter, as in the example of the 

 white and yellow carrots; (6), by earlier or later maturity, earlier maturity 

 inducing more heightened color; (c), by the restoration of normal nutri- 

 tion to a " variegated " stock or scion; (d), by the transfer to a healthy 

 stock of the disease known as variegation. There is little evidence that 

 the characteristic color of fruits is modified by grafting. 



9. Flavor.— The testimony is abundant that fruits may acquire the 

 flavor of the fruit of the stocks on which they are grafted; this has been 



