30 



HORTICULTURAL MANUAL. 



Aside from scientific theory this would clearly show that 

 cell-forming material descends near the cambium layer. 

 In the same line, if we remove a ring of bark in June 

 from the stem of an apple-tree we obstruct the downward 

 movement under the bark. Soon we begin to observe a 

 process of healing over the wound by cell-formation on 

 the cut surface above the ringing, and as the season 

 advances we notice that the ripened 

 and mature condition of the wood 

 above has changed leaf-buds into 

 fruit-buds. Again in spring bud- 

 ding, those with most experience 

 make the cross-cut of the T below, 

 and shove the bud upward as the 

 cross-cut above obstructs the move- 

 ment of the assimilated food from 

 the leaf. 



In regard to sap-pressure we have 

 also a good example in working 

 FIG. 12. An old cleft scions on uncongenial stocks. As 



graft, showing point of instances, the apricot on myrobalan 



union of stock and 



scion. stocks makes no real union of cells. 



The cells of the apricot rest on cells of the myrobalan. 

 The growth seems to be thrifty and unimpeded, but the 

 winds usually topple them over before they reach the bear- 

 ing-stage. When blown over it is found that there is no 

 rupture of cells, but a clean separation of the two woods. 

 Where the stock and scion are so nearly allied that the 

 union of cells takes place, breaking down causes rupturing 

 of the wood. Yet the wood of the stock and scion remain 

 distinct. If orange is budded or grafted on lemon the 

 shoot that starts from the stock half an inch or less below 

 the union will be lemon. But what are known as (( graft 

 hybrids " have come from sprouts from the point of union. 



