218 



APPLICATION OF PRINCIPLES. 



of tbe stock is very imperfect, because the bark 

 of the former necessarily lies upon the wood of 

 the latter, except just at the sides; and, from the 

 impossibility of bringing the two barks in contact, 

 neither the ascending nor descending cur- 

 rents of sap are able freely to intermin- 

 gle. This plan, much improved by cut- 

 ting out the stock into the form of a wedge, 

 instead of splitting it, may, however, be 

 advantageously employed for such plants 

 as Cactaceae {fig. 26), the parts of which, 

 owing to their succulence, readily form a 

 union with each other. 

 A far better method than whip-graft- 

 ing, but more tedious, is saddle-graft- 

 ing {fiiQ. 27) ; in which the stock is 

 pared obliquely on both sides till it be- 

 comes an inverted wedge, and the scion 

 is slit up the centre, when its sides are 

 pared down till they fit the sides of 

 the stock. In this method, the great- 

 est possible quantity of surface is 

 brought into contact, and the parts are 

 mutually so adjusted, that the ascend- 

 ing sap is freely received from the 

 stock by the scion, while, at the same 

 time, the descending sap can flow 

 freely from the scion into the stock. 

 Mr. Knight, in describing this mode of operating, has 

 the following observations : 



" The graft first begins its efforts to unite itself to 



