264 DISEASE IN PLANTS. 



no point more than on whether the scion can affect 

 the stock, in spite of such examples as Cytisjis 

 Adaini, Garreya on Aucuba, Sunflower on Jerusalem 

 Artichoke, etc. Recent results, especially of ex- 

 periments with herbaceous plants, show that not 

 only can the stock affect the scion (and vice versa) 

 directly, but the effect of the changes may be 

 invisible on the grafted plant and only show itself 

 in the progeny raised from the seed of the grafted 

 plant. In other words, variation occurs in grafts 

 either directly, as the results of the effects of the 

 environment on the graft, or owing to the interaction 

 of scion and stock, showing as changes in general 

 nutrition in the tissues concerned, etc., owing to 

 special reactions of the protoplasm of the uniting 

 cells one on the other, and of the results of the 

 further protoplasmic secretions, sortings, and so 

 forth, on the cells developed as descendants of 

 these in the further growth of the graft : or 

 indirectly, in that some of these changes so alter 

 the nature of the special protoplasm put aside for 

 reproductive purposes, that the resulting embryo 

 in the seed transmits the effects, and they show as 

 variations in the seedling. If these results are 

 confirmed they should meet all objections that 

 have been urged against the transmission of 

 acquired characters. 



In fact there are analogies between grafting and 

 parasitism which cannot be overlooked, and should 

 not be underestimated, their commonest expression 

 appearing in the alterations in stature, habit, 

 period of ripening, and so forth. These analogies 



