GRAFT-HYBRIDS AND OTHER CAIMERAS 383 
Modification of One Graft-symbiont by the Other.—The repressing 
or stimulating effects of certain scions on certain stocks is well known. 
Excellent examples are found in the various ‘dwarf’ rootstocks used in 
the culture of the pome and citrous fruits. Besides the dwarfing effect 
of the stock upon the scion, there is often a reciprocal stimulating effect 
of the scion upon the stock which causes the latter to increase in diameter 
faster than the scion. A mutually stimulating effect is sometimes ob- 
served, as in the almond and the peach when used as graft components. 
The importance of selecting stock of about the same vigor, when grafted, 
as the scion has long been recognized by nurserymen. The fact that 
grafts usually exhibit a certain amount of modification according to the 
kind of stock used has given rise to many reputed cases of deleterious 
effects and extreme modifications due to grafting. 
A matter of considerable economic importance involving this question 
concerns the culture of wine grapes. After the introduction of American 
vines and their hybrids into the phylloxera-infested districts of France 
there was widespread concern over the possibility that the quality of the 
French wines would be injured by grafting on the new stocks. Many 
investigations were carried on. Although in the earlier stages of the 
work some very definite effects of stock on scion were reported, the 
evidence as a whole is considered by leading investigators as indicating 
merely that the stock may either increase or decrease the capacity of the 
scion according.to the combination used. It has been concluded that 
where due account is taken of affinity of stock and scion, if other condi- 
tions are favorable, grafting has caused no deleterious effect on yield or 
quality. 
A specific case of supposed deleterious effects attributed to the in- 
fluence of stock on scion was observed by Paelinck. A dark-red variety 
of cherry, Early Rivers, was grafted on mahaleb stock. The resulting 
tree bore fruit which was yellowish white in color, of smaller size and 
which matured 8 days later than Early Rivers. Scions from this white- 
fruited tree were grafted on mazzard stock which has small black fruit 
“‘to see whether the white fruits would revert to the dark color.’’ The 
result as one would expect was negative. Undoubtedly this was a case 
of bud mutation. 
Other reputed extreme effects of graft-symbionts involve the supposed 
transfer of characters from the one to the other. Baur asserts that after 
reviewing the accounts of many grafting experiments he has reached 
the conclusion that most of the reciprocal effects between stock and 
scion can be explained on the basis of modification in nourishment. 
Moreover, where this explanation does not hold there is a more probable 
cause than the notion of transfer of characters. For example, in the case 
of Daniel’s eggplant which, when grafted on tomato bore tomato-shaped 
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