GRAFTING AND NURSERIES. 



227 



to leave the slit open and facilitate the insertion of the 

 tongue. The object is to consolidate the assemblage, but 

 it also facilitates the production of callus. For, as already 



Fig. 09. 



Sections of Stock and 

 Scion. 



Fig. 100. 



Joint of whip-tongue 

 graft. 



explained, callus will be produced in greater abundance on 

 a longitudinal than transverse section. Further, the callus 

 first appears on the inner walls of the slit. 



The point where the slit is made has not very great 

 importance, and the pith need not enter into consideration. 

 The pith, contrary to the old belief, does not play any part 

 in the life of the plant; it can be removed without incon- 

 venience. But what is more important is that the 

 point where the slit begins and the point where it ends be 

 at an equal distance from the centre of the section, so as to 

 allow their exact juxtaposition (Fig. 99). Therefore, the 

 closer to the centre the shallower the slit will be. If it is 

 not made in the way indicated, the adjustment will be 

 defective ; if too short, the sections could not cover each other ; 

 if too long, the joint will lack in strength. 



