INTESTINAL PROTOZOA OF TERMITES. 1 87 



r -books of chemistry and physiology give little, if any, of the 

 information which has been gained in recent researches on the 

 chemistry' and digestion of cellulose, it seems expedient to briefly 

 mention with no pretention at a discussion some of the salient 

 features brought out by a few of the more important of these 

 researches. 



According to Hibbert (1921) "cellulose is nothing more than a 

 polmerized dextrose glucoside of dextrose," and Irvin and Hirst 

 (1922) in their most recent paper on the constitution of poly- 

 saccharides have shown this to be true. They state that "the 

 average yield from the polysaccharide (e.g., cellulose) to the 

 hexose (e.g., glucose) is thus 95.5 per cent, of the theoretical 

 amount. Considering the standard of purity in which the mixed 

 methylglucosides were isolated, there can be no further doubt 

 that cotton cellulose is composed entirely of glucose residues." 



1'ringsheim (1912) observed cellobiose a disaccharide which 

 bears the same relation to cellulose that maltose does to starch 

 and which spilts into two molecules of glucose (Fischer and Zem- 

 plen, 1904 and 1910), when acted upon by cellobiase as an in- 

 termediate product of bacterial cellulose digestion. The exact 

 mode of linking together of the two glucose residues in cellobiose 

 was determined by Haworth and Hirst (1921). Groenewege 

 (1920) showed that the bacterial digestion of cellulose is a hydro- 

 lytic procoss. 



Celluluse is known to be produced by various moulds, soil 

 fungi, pathogenic fungi, actinomycetes, soil and intestinal bacteria. 

 Cellase is to be distinguished from cellulase in that it acts on the 

 hemicelluloses and is not an endo-enzyme (Pringsheim, 1912). 



Some rather divergent views have been expressed regarding 

 the products of cellulose digestion ; different investigators working 

 with different cellulose-decomposing organisms have gotten dif- 

 ferent results. But according to Cross and Doree (1922) most of 

 these differences may be accounted for. The typical result of 

 i he digestion of wood cellulose is about as follows: Cellobiose, 

 ij 1 1 cose, acetic acid, lactic acid, butyric acid, alcohol, CO 2 , H 2 , 

 CH 4 , CO. l'nder excessive aeration alcohol and acetic acid are 

 i-i'inpletely oxidized to CO 2 and H 2 O. The gas liberated is never 

 I >ii re CO 2 ; there is either H 2 or CH 4 , or a mixture of the two. 

 Alcohol is never obtained without acetic acid. \Yuksman (19-- 



