1 82 



I'LAiNT rivOPAGATION 



made analj'scs of pear trees two years old from the graft on 

 fjuince and pear stocks to determine the relative quantities of 

 ])lant foods stored in the stems of the two sets of plants. It was 

 found that during autumn and winter reserve matter was markedly 

 more ahundant in the stem on quince stock. In spring", therefore, 

 the pear on quince was enaljled to furnish more food matter for 

 fruit formation and crop production was greatly increased. Again, 

 reserve food in stems is nearer the fruit than in roots and is thus 

 possibly more readily utilized. If these experiments are accurate 

 we may find the liest stocks are those whose roots store the least 

 quantity of reserve-foods and so force the accumulation of re- 

 serve matter in stems. 



Unquestionably, some effects of stock are due to altered nutri- 

 tion — possibly to insufficient nutrition of stock or cion. Much evi- 

 dence points to disturbance of nutrition as the chief cause of the 



FIG. 155— HERBACEOUS GRAFTING AND BUDDING 



1, herbaceous buds; 2, herbaceous grafts. Summer methods of propagating 

 grapes on green canes. None of the herbaceous methods so far tested in California 

 have been veiy successful. 



efTects of grafting. It may be that food elaborated by the foliage 

 of the cion is different from that the stock would have had with 

 its own foliage. It has been suggested that difference in specific 

 gravity of stock and cion sap may be a disturbing factor. But 

 these explanations are not sufficient to cover all phenomena arising 

 from grafting. Truth is we ha\e for the most part only certain 

 isolated facts to explain which we must rely upon inferences 

 which have the greatest amount of probability in their favor from 

 the knowledge of the case. It remains for someone to tell why. 

 230. Why nurserymen bud or graft trees.— Important though the 

 effects of stock are on cions, any and all are hut incidental to the 

 true explanation for a two-part tree for practically all orchard 

 plants. At the proper season in e\ery nursery an army of expert 

 workmen graft or bud so dexterously, precisely and rapidly that 

 their work is little short of marvelous. What are the reasons for 



