8o THE VEGETATIVE FUNCTIONS OF PLANTS 



5. The conversion of dextrin into soluble starch 

 (amylum) by amylase. 



6. The conversion of soluble starch into insoluble starch 

 by yet another ferment or enzyme, coagulase. 



Other analyses of the process of photosynthesis have 

 been suggested, and it is possible that the one outlined 

 above may become more or less modified in the light of 

 future experiments. 



80. Storage of Food. As stated above, some of the 

 food elaborated in the leaves is transferred to various 



FIG. 59. Starch grains from a potato tuber. (After Duncan J. Reid.) 



other parts of the plant. Some of it is used immediately 

 to nourish these parts, but often this food accumulates 

 faster than needed. This is what always occurs in certain 

 parts of the plant, such, for example, as the tubers (under- 

 ground stems) of potatoes (Figs. 59 and 60), the roots of 

 turnips, the seeds of beans, peanuts, and other plants, 

 the fruits of all plants, the leaf-base of the onion (form- 

 ing the scaly bulbs or " onions "), and all buds when 



