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 (Lycopersicum), 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 each come in 
contact, and then binding the two together (Fig. 242). 
In time the two tissues become firmly united, grow- 
