THE RECIPROCAL INFLUENCES OF STOCK AND CION 569 



acidity of the wound surface. In a word, these results show very clearly 

 that the graft, considered by itself, modifies the regimen of water and 

 of soluble salts, that is to say, of the functional capacities of the grafted 

 plants." 



In support of this view he cites Viala and Ravaz to the effect that the 

 Herbemont grape was free from chlorosis on Clairette; likewise Merlot 

 on Viala. It seems possible that these last instances may be due to a 

 high degree of congeniality between the varieties mentioned. Blunno^* 

 states that many resistant stocks are without chlorosis until they are 

 grafted, but become so afterward, explaining this through the weakening 

 of the plants by grafting. Susceptibility is greater, he reports, when the 

 graft is not well healed and any weakening influence such as a fungus or 

 insect pest, even on a resistant variety, favors infestation by phylloxera. 



Since John Lawrence, ^^ in 1717, noted the transmission from the cion 

 to the stock of variegation in leaves, this fact and its converse have been 

 cited as standard evidence of the influence of stock on cion or of cion on 

 stock or both. Numerous instances of such transmission are easily found, 

 but have lost much of their significance through the view that in many 

 cases variegation is a pathological condition and that grafting is in such a 

 case also an inoculation. Variegation arising from other than patho- 

 logical causes seems not to be transmitted from stock to cion or from cion 

 to stock. 



Yield. — Some commentators are disposed to believe that grafting 

 per se disposes the plant to fruitfulness. This is well expressed in this 

 statement: "Seedling apples, especially those which are of a vigorous 

 nature, run to wood and produce few fruits, or begin very late to produce 

 them. Grafted apples, on the contrary, begin earlier to fruit." ''^ . . . 

 Undoubtedly early bearing is favored by grafts which have not united 

 perfectly, just as it is by ringing or by any influence obstructing trans- 

 location. Whether grafts which unite readily have the same effect is 

 not so clear. Precocity of bearing is necessary to the success of any 

 variety in cultivation; deficiency in this respect is the chief objection 

 to the Northern Spy apple and the chief reason that it is now so little 

 planted. Naturally, then, grafted trees of cultivated varieties tend to 

 come into bearing early; otherwise the varieties would not be in culti- 

 vation. Some varieties come into bearing at an earlier age than others, 

 though all are grafted presumably on the same stocks. This time can 

 be hastened or retarded by cultural means. Vigorous seedlings are 

 late in bearing; so are vigorous grafted trees. There seems no clear 

 evidence that grafting in itself, as commonly practiced in fruit trees, 

 hastens the time of bearing. 



The influence of different stocks on the functioning of the cion is 

 shown neatly by experiments such as those of Lindemuth'-** on potatoes. 

 This investigator found that the potato on Datura, a vigorous growing 



