ORGANIC COMPOUNDS OF PLANTS 179 



In seeds, it is a reserve material, finally used as food by 

 the young plant. Commercially, cellulose is used for 

 making paper, cloth, guncotton and other explosives, and 

 is extensively used in the arts. 



231. Food Value. The food value of cellulose depends 

 upon its degree of hydration. Hydrated cellulose, when 

 digested, has practically the same food value as starch. 

 Lignocellulose is indigestible, and has no food value. 

 Indirectly, a minimum amount of cellulose imparts a 

 mechanical value to a food by acting as an absorbent for 

 concentrated waste products. When crops are cut and 

 cured while some of the cellulose is in a hydrated condi- 

 tion and but little has passed into the ligno form, the 

 cellulose is valuable as food. 



232. Amount of Cellulose in Plants. Cellulose is 

 found more abundantly in the stems and leaves of plants 

 than in the seeds. In the straw of wheat, oats, rye, and 

 barley, it makes up from 35 to 45 per cent, of the dry 

 material. It also constitutes a large portion of the roots 

 of plants. In seeds, the amount of cellulose is small, and 

 usually ranges from 2 to 5 per cent. , while in wood, the 

 amount is large, and ranges from 50 to 80 per cent. In 

 tables of analyses, the cellulose is usually included with 

 other bodies under the head of crude fiber. 



233. Crude Fiber. Crude fiber includes the cellulose, 

 lignin and other bodies which make up the framework of 

 vegetable substances. In vegetable foods, as flour and 

 the cereal products, the amount of crude fiber is small 

 compared with that in many other plant bodies. Crude 



