452 THE MONTHLY BULLETIN. 



more acid and sugar^y, is less rich in phosphate, more highly charged 

 with nitrogenous matters, has little tannin, less color, and the color is 

 less stable ; the vines are more fruitful ; the fruit matures earlier. These 

 differences vary in different cases. From the fact that the color is less 

 stable and the proportion of the nitrogenous matters in the must is 

 greater, the wines from grafted vines are said to mature more rapidly 

 and are more sensible to injurious fermentations. 



In an experiment with grape stock for American grapes, carried on 

 for eleven years at the New York Station, we found material differences 

 between grafted and ungrafted vines, all included in the above summary. 



There is no doubt, I must say in passing, a reciprocal influence of the 

 scion on the stock. We know certainly, for example, that the form of 

 the roots is much changed by the scion. Thus, in starting apples in a 

 nursery we graft or bud on seedlings which ungrafted would have root 

 systems much the same but at digging time the roots are as diverse as 

 the varieties; Red Astrachan, for instance, has an exceedingly fibrous 

 root system with few tap roots, while on either side of the Red 

 Astrachan row Oldenburg and Fameuse are almost destitute of root 

 fibers, having instead a deep tap-root and two or three prongs. So it is 

 with practically all fruits, though not as noticeable with any as in 

 apples and pears. Nurserymen tell me, the weaker the top-growth and 

 the sparser the foliage of a variety, the more deficient is the root- 

 growth. 



To the general rule that allied species grafted together retain their 

 identity, there are a few exceptions in which the scion acquires char- 

 acters from the stock or the stock from the scion — the graft-hybrids of 

 experimenters. There are on record- a sufficient number of such hybrids, 

 or pseudo-hybrids, to make out a case for hybridism through grafting. 

 It would be interesting and profitable to consider in detail the several 

 supposed graft-hybrids, but as none have i^ractical value they are more 

 suited to controversy than to real life — mentioned here simply to show 

 the possible extremity of the mutual influence of the stock and graft. 



AVhat are the explanations for these various reciprocal effects of stock 

 and scion ? Plant physiology does not help us much in the elucidation 

 of the influences of grafting. Theoretically, from the anatomy of plants, 

 we can expect nothing more in grafting than the adhesion of the graft 

 to the stock. The tissues below the union are those of the stock ; above 

 it, those of the scion. Yet there is some reason to suspect that definite 

 substances pass from one to the other in the consoi'ting parts of a 

 grafted plant and produce specific effects. Thus, as we have seen, when 

 a scion with variegated foliage is grafted on a normal stock, shoots 

 which spring from the stock below the graft are variegated. Or, if the 

 deadly nightshade be grafted on a tomato the poison, an alkaloid (atro- 

 pine) passes down into the stem and root of the tomato. But curiously 

 enough, if the variegated plant or the nightshade be used as a stock the 

 variegation in the one case and the atropine in the other do not pass 

 upward into the scions. 



An ingenious and not at all improbable reason for some of the influ- 

 ence of the stock upon the scion was offered by a speaker in the French 

 Academy of Science. He had made analyses of pear trees two years 

 old from the graft on quince and pear stocks to determine the relative 

 quantities of hydrocarbons stored in the stems of the two sets of plants. 

 It was found that during the autumn and winter the reserve matter 



