STEMS 



131 



What happens to the mercury? Can you account for 

 this? How? What does this show? 



Budding and Grafting 



In Experiments 86-88 artificial propagation by cuttings 

 and layers was considered. In that method, the propagation 

 of new individuals is due 

 to the ability of a plant 

 to put forth adventitious 

 roots. But it is often 

 desirable to change a 

 plant in order to make it 

 produce a different sort 

 of fruit. This is accom- 

 plished by budding or 

 by grafting. 



The following princi- 

 ples must be strictly ad- 

 hered to if this method 

 of propagation is to suc- 

 ceed : 



1. Only closely related 

 dicotyl plants can be en- 

 grafted upon one another. 

 Thus apples of different 

 sorts can be made to 

 grow upon other apples, 



pears, quinces, crab apples, etc., but they cannot be made 

 to grow on peach, plum, or cherry stocks. 



2. The union between the living tissues (cambium) of both 

 plants must be perfect. If the living parts do not actually 

 touch, they cannot unite and grow together. 



FIG. 54. Sap pressure : g, gauge tube ; st., 

 rubber stopper ; m, mercury ; PL, plug ; 

 w, T-tube ; con, rubber connection ; PI. 

 St., plant stem ; Pt., flowerpot. 



