SAPROPHYTISM AND SYMBIOSIS 



335 



onto the main stem or branch of another species. This is 

 accomplished by placing the freshly cut surface of 

 the scion against the freshly cut surface of the stock, 



FIG. 243. A tomato (Ly coper sicum), grafted on a potato (Solatium). 

 Note the potato tuber on the surface of the soil. Cf. Fig. 404. 



in such a way that the cambium layers of both come in 

 contact, and then binding the two together (Fig. 242). 

 In time the two tissues become firmly united, grow- 



