RESERVE FOODS 



279 



Date seeds and Ivory nuts is due to the hemi-celluloses, in which 

 form these seeds store their reserve food. (Fig. 250.) 



The fats are prominent storage forms of food in a number of 

 plants and usually occur in the form of oils, known as fatty oils. 

 They contain the same elements as the carbohydrates, but have 

 much less oxygen in proportion to carbon, and the hydrogen and 

 oxygen are not present in the proportion to form water. The 

 vegetable fats are chiefly compounds of 

 glycerine and fatty acids. Palmitic, 

 oleic, and stearic acids are the fatty 

 acids commonly found in fats, but there 

 are many others, and the character cf the 

 fat formed depends much upon the kind 

 of fatty acid entering into the combina- 

 tion. The fatty oils are usually stored 

 in the seeds, but often in the flesh of 

 fruits and other portions of the plant. 

 Olive oil which is pressed out of the fruit 

 of the Olive, Corn oil from the embryos 

 of Corn, Cotton-seed oil from Cotton seed, 

 Coconut oil from Coconuts, Linseed oil 

 from Flax seed, and Castor oil from 



seeds of the Castor Bean are well known * vory ut ' showin g the ex- 



I'M i i . , treme thickening with hemi- 



plant oils and have an important place cellulose, which is deposited 



in our industries. in i ayers forming striations. 



The fatty oils are usually present in The walls are perforated by 



the storage cells in the form of globules, the canals through which 



and like starch are insoluble in the cell the P rot P; asmic strands 



v / i ,, t , . pass. Highly magnified, 



sap. Before being consumed by the plant 



as food, they are converted by means of enzymes into simpler 

 and soluble forms, such as glycerine and fatty acids. 



The vegetable fats are not only important animal foods, but 

 are used in many ways by man in the industries. Rape oil and 

 Corn oil are much used for lubricating machinery. Linseed oil 

 is extensively used as a solvent for paint. Palm oil, Cotton-seed 

 oil, and Coconut oil are made into substitutes for butter, besides 

 being used in many other ways. Castor oil, besides being used 

 as a medicine, lubricant, and illuminant, is used in manufacturing 

 dyes. The use of Olive oil in foods is well known. Many of the 

 vegetable oils are used in making the best soaps. 



FIG. 250. Cell walls of 



