PLANT PRODUCTS 



135 



of the season, but is found in greatest abundance in such special 

 storage organs as bulbs, tubers, fleshy roots and seeds. It is 

 found in very great abundance in f raits, and is the most abundant 

 food compound in all nature. It is used more extensively than 

 any other food product. 



The percentages by dry weight of starch in some of our most 

 important food plants are as follows : potatoes, 80 per cent. ; 

 wheat, 68 per cent, ; 

 rice, 68 per cent. ; 

 corn, 60 per cent. ; 

 pears, 52 per cent,, 

 and navy beans, 45 

 per cent. 



Inulin is an iso- 

 mer of starch which 

 is found in solution 

 in the cell sap of 

 many plants and is 

 readily crystallized 

 by alcohol (Fig. 



N T . . rone, (d) cells containing starch. 



95). It is abundant 



in the underground organs of many plants, especially the roots 

 of the dahlia (Fig. 95). Although of some importance to the 

 plant, it is of very little importance as a food for animals. 



The sugars are the products of photosynthesis and are very 

 abundant and very widely distributed crystalline compounds. 

 They are very closely associated with starch, into which they are 

 readily converted. They are also very readily reconverted into 

 sugars. The most important sugars are as follows : 



(a) Dextrose (grape sugar or dextrose-glucose) is found in 



FIG. 92. Section of grain of wheat; (a) ovary 

 coats, (b) seed coats, (c) layers of cells containing aleu- 



