140 



PLANT PROPAGATION 



the two kinds of wood; what is its nature? How definite 

 is it? Is it physically strong or weak? Would answers 

 to these questions be more than speculations? It must 

 be remembered, however, that such answers are beyond 

 the conclusions cited above and that the facts so far 

 presented are not affected by the following- discussion. 



Sections of grafts 

 (Fig. 124) show that 

 in spite of the longitu- 

 dinal continuity of the 

 annual layers there is 

 sometimes a plainly vis- 

 ible line of demarca- 

 tion between the wood 

 of stock and cion at 

 right angles to the 

 longitudinal growth, yet 

 reveal the secret of 



FIG. 124 CHERRY CION ON PLUM STOCK 

 Notice continuous annual layers of wood. 



not 



the microscope does 



individual cells which compose the tissue. One 



can nearly always see less with the microscope than with 



the naked eye! In the section shown in Fig. 132 and 



magnified about 1,000 



times, the little knot near 



the middle accidentally 



shows one point on the 



line of junction, but the 



vessels and the cells run 



from end to end without 



interruption. So it is 



harder than ever to see 



where stock ends and 



cion begins. Hence 



those gardeners who 



have been dreaming of 



producing new kinds of FIG. 125 DEFECTIVE PEAR BUD GRAFT 



plants by grafting must ON QUINCE STOCK 



needs Wake Up ; for HO Probab .'y du ?. to . incompatibility of stock and 



cion. Notice cleanness or break, 



