SAPROPHYTISM AND SYMBIOSIS 



335 



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

 accomplished by placing the freshly cut surface of 

 the f scion against the freshly cut surface of the stock, 



FIG. 243. A tomato (Lycopersicum}, grafted on a potato (Solanum). 

 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- 



