

36.] CHAPTER II. THE TISSUES. 215 



Stems of plants of the same species will grow together if they 

 are in close contact ; the callus formed by the cortex of both, 

 coalesces and gives rise to a common cambium. On this depend 

 the various modes of artificial grafting, in which branches or buds 

 with a portion of the cortex are taken from a variety or an allied 

 species and placed so that their cambium is in contact with that 

 of a stem which serves as the stock, and subsequently they grow 

 tog-ether. 



