118 



THE HEALING OF WOUNDS 



The careful observer will often see the callus 

 of wood wounds growing most rapidly from the 

 upper side. In Fig. 88 the bark has grown down 

 over the wound. In Fig. 75, the point of union 

 of the opposite sides of the callus 

 ring is at 6. This stub stood hori- 

 zontal on the tree, and 6 was the 

 lower side. The union of cion and > 

 stock sometimes acts as an obstruc- 

 tion to the free downward movement 

 of sap, causing a bulge on old 



98. 



Suggestion to prevent gall- 

 ing of a staked tree. 



99. Bridge-grafting 

 of a girdled trunk. 



top -grafted trees; but this phenomenon should 

 not be confounded with the normally more rapid 

 growth of some cions, due to the variety, as com- 

 pared with that of the stock (see Fig. 133, Nur- 



