PROPAGATION. 217 



be spared for the purpose. Much may be done in this 

 way among exotics by an ingenious cultivator who 

 may have a hot bed to plunge his root-grafted plants 

 into : such a stimulus greatly assists operations of 

 this nature. 



Whichsoever manner of grafting be adopted, the 

 success principally depends on the congeniality of the 

 stock and graft, on the proper season chosen for doing 

 it, and on the precision and expedition with which 

 the operation is performed. 



Reverse grafting. Nothing shows the anastomos- 

 ing properties of the cellular membrane, when 

 actuated by the vital principle, so convincingly as the 

 instance of reverse grafting. By placing a graft on a 

 stock in this unnatural manner a perfect union takes 

 place and the future development of the graft is carried 

 on in the same way as that of a reversed shoot. In 

 this case it is perceivable that, if there be special sap 

 vessels, they can re-convey as well as convey the juices 

 either upwards or downwards ; or if there be no such 

 vessels, it is evident, as has been before stated, that 

 the cellular frame is permeable by sap in all directions. 

 Another proof of this is exemplified by the long 

 rambling shoots of the common bramble, which, as 

 soon as their points rest on the ground, strike roots 

 and assist to amplify the shoot by a backward flow of 

 nourishment. 



Budding Differs from grafting in this, that, 

 whereas by the latter, a shoot or part of a shoot 



