CELLULOSE FERMENTATION 183 



the animal kingdom. (2) It is composed of the same elements — 

 carbon, hydrogen, and oxygen — ^as the sugars. Moreover, many 

 of the sugars contain these elements in the same proportion as 

 does the cellulose. (3) Cellulose has no nutritive value for man, 

 yet one of the dietetic errors of modern man is that his food does 

 not contain sufficient quantities of it. It gives to the food bulk, 

 and hence forms leverage on which the intestines can act. It is 

 reported that sawdust and wood shavings, which are largely cellu- 

 lose, were used by the Germans in the late war as a cattle food 

 and in war breads. Cattle, due to the bacterial flora of the 

 alimentary canal, may utilize some cellulose, but it is doubtful if 

 man would be nourished by its use. (4) Cellulose is insoluble in 

 all of the common solvents such as alcohol, ether, and water. 

 If treated with sodium hydrate, it will dissolve in carbon bisul- 

 fide, and if the resulting yellowish liquid is squirted through fine 

 holes into acidulated water we have fine threads of artificial silk. 

 (5) Plants secrete a digestive ferment which will break down 

 cellulose. This is especially true of some fungi, bacteria, and 

 germinating seeds. No animals secrete such a ferment; hence, 

 when cellulose is digested by animals it is due to the bacteria 

 which they harbor in their intestines. 



Cellulose in Soil. — ^The organic matter of the soil originates 

 from the plants — either those which have grown upon the soil or 

 those which have been carried there by various processes, princi- 

 pally as manures. Where wheat is grown upon the arid soils of 

 western America and harvested with the header or combined har- 

 vester from one to two tons of roots, straw, and chaff may be 

 left upon the soil, depending upon the size of the crop and the 

 method used in harvesting it. 



Assuming that one ton of straw is left, it would carry back 

 into the soil ten pounds of nitrogen, two pounds of phosphorus, 

 and ten pounds of potassium, as well as 1,700 pounds of dry mat- 

 ter, about 50 per cent of which is cellulose. That is, one ton of 

 straw carries to the soil approximately 850 pounds of cellulose. 

 When alfalfa and plant residues are returned to a soil, propor- 

 tionately smaller, but appreciable, quantities of cellulose are being 



