RESISTANT VINES; THEIR SELECTION, ADAPTATION, ETC. 39 



tact with one another, that form the joint. The younger they are at the 

 moment they join (that is to say, the less their cells are suberified), the 

 better will be the joint. It will be seen from this that the various 

 regions of the bark should be placed as close together as possible. The 

 cells which are derived directly from the activity of the generating layer 

 become joined; one of their layers is transformed, and becomes generat- 

 ing tissue, and unites with the generating tissue of the stock. From 

 this moment the grafted stock grows normally till the joint is com- 

 pleted from the top to the bottom of the wound, and performs its functions 

 as though no wound had been made, and forms wood on the inside and 

 bast on the outside. 



If the bumps of callus be put in contact when they are old, the joint 

 is far less perfect, and although a joint will form, it will be a very poor 

 one. The tissues are derived from the activity of the new generating 

 layer, and differentiate so as to continue either the libroligneous bundles 

 or the medular rays, etc., corresponding to the graft and the stock. 

 There will, however, be numerous anastomoses formed, thus enabling 

 the circulation to take place almost as though there had been no inter- 

 ruption made in the tissue made by the graft. 



Such is very roughly the mechanism of the joining of the graft with 

 the stock. From the foregoing we have supposed that the subject or 

 stock was a shoot or part of a branch more or less aged. One could, 

 however, have equally well taken a root or portion of one as the stock. 

 The large roots of the vine have (save a few bands of bast fibers) 

 sensibly the same structure as the cane from one to three years of age. 

 In such a case the joint is produced in the same manner as above 

 described. 



The cicatricial tissue does not form equally well with all varieties of 

 the vine, whether used as a graft or as the stock. This is observed in the 

 case of a large number of other plants. Some will scarcely form a 

 callus at all, while others form it with the greatest facility. In the case 

 of the vine, the divers varieties have this peculiarity in a very marked 

 degree. Thus we note abundant callus, hence easy grafting, in the case 

 of the Berlandieri (which, however, will not grow from cutting), the 

 Vitis Cinerea, Rupestris St. Georges, Vialla, Cabernet Sauvignon; and a 

 very poor grafting power in the case of the Solonis, Folle Blanche, etc. 



But independently of the nature of each variety, the formation of 

 tissue is profoundly modified by other exterior agencies. According 

 to Prof. Millardet, callus is most rapidly formed at a temperature of 

 68 F. Some, however, maintain that a temperature from 87 to 95 F. 

 is more favorable, but beyond this the graft will suffer. Below 60 F. 

 the formation of callus is very slow indeed. What is essential is that 

 the temperature should be sufficiently great, but always regular. The 

 greatest amount of callus is found in the case of grafts buried in light, 

 warm soils at a depth sufficient to cause the variations of heat to be as 

 light as may be. 



The degree of humidity of the soil exerts a very great influence on 

 the successful joining of the graft to the stock. If a cutting or a grafted 

 cane be plunged into water so as to cover the lower parts of the cane, 

 no cicatricial tissue whatever will form.^ Grafts covered with fine sand, 

 kept constantly wet by irrigation, may put out young shoots, but will 

 never form a joint. This is frequently noted in the case of stratified 



