IV.] 



BOTANY. 



often marked* with concentric rings, and is tinged 

 bright blue with iodine. It is found in greatest quan- 

 tity in the parts of plants intended to be deposits 

 of food during winter, for the growth of the plant 

 in the following spring. Seeds and roots, as they 

 grow, use up the starch which the cells contain. 



FIG. 6. Starches. Granules of a Potato, b Wheat, c Oats, d Maize ai d 

 Rice, e Bean and Pea, f Parsnip, g Beet ; all very many times their real size. 



18. Oils and fats are composed of the same 

 elements as starch, from which they are probably 

 manufactured by the plant, and as deposits of food 

 serve the same purpose. Oils prevail in seeds and 

 fruits, as linseed oil (from the seed of the flax -plant), 

 cocoa-nut-, almond-, olive-, colza-, and castor-oils. 



19. Sugar, formed also of the same elements, 

 differs from all the preceding in being soluble in 

 water, and existing only in solution. It abounds in 

 the cells of sugar-cane, beet, parsnip, and all sweet 

 fruits. It is formed out of the starch manufactured 

 in the leaves. 



20. Albuminoids. These are compounds con- 

 taining nitrogen in addition to carbon, hydrogen, and 



