172 



ri.ANT I'KOI'ACATION 



also that these variatiuns, which the experimenter classes as 

 specihc, are at least in certain cases transmitted by the seed. 



Daniel also concludes that grafts may influence the somato- 

 plasm (223), though not always. In many plants the effect is often 

 very slight, especially in woody plants in which the ligneous frame- 

 work gives to the plant a much more iixed form than herbaceous 

 plants possess. When this influence exists, it most often affects 

 characters of little taxonomic importance, as height, vigor, etc., 

 and then its influence is similar to that of environment; but it may 

 sometimes affect the essential characters of varieties or species, 

 such as external form, structure, etc.. which become more or less 

 blended into graft hybrids (228) or may disappear, giving place 

 to new characters. Not only may the influence of the graft on the 

 somatoplasm show itself directly in the grafted plants themselves, 

 but it may produce an indirect reaction either parallel or not par- 

 allel to the direct reaction, and new characters may develop in 

 the offspring, proving that, contrary to Weismann's theory, acquired 

 characters can be transmitted in the vegetable kingdom. 



From his theoretical considerations, Daniel deduces 

 certain practical conclusions. When grafting does not 

 modify the peculiar characters of a variety, but mereh' 

 produces certain slight variations of nutrition, it ma}' l)e 

 einployed to ])erpetuate varieties, races, 

 or accidental forms of ])erennial plants ; 

 but if the influence of the graft on the 

 somatoplasm is ver}- marked and proves 

 to be specific (which experiment alone 

 can determine), it may be applied to the 

 creation of new varieties. Here a new 

 field of operation is opened up to seeds- 

 men. 



There are numerous practical appli- 

 cations of the reciprocal eft'ect of stock 

 and cion, such as increase in size of 

 fruits, improvement of flavor of fruits 

 and certain vegetables, production of 

 new varieties in which color of flower, 

 form of fruit, or vegetative organs are 

 modified. The effects of grafting are more 



FIG. 146— , , ■ , , xl • 1 



WIRE PROTECTOR marked m herbaceous than m woody 

 '^''*"^§Ibb,tJ'- "^^ plants and al.^o more marked in the oft- 





