PROTOZOA AND OTHER ANIMALS 961 



Physiological Host Relationships Illustrative of 

 Mutualism and Commensalism 



FLAGELLATES OF TERMITES AND CvyptOCerCUS 



Before discussing the relationship between the xylophagous flagel- 

 lates and their wood-eating termite or roach hosts, it is desirable to give 

 consideration to the problem of nutrition in some other invertebrates 

 that ingest material consisting largely of cellulose. 



The most abundant single constituent of wood is cellulose, which aver- 

 ages in general between about 54 and 64 percent (Pringsheim, 1932 

 after Schorger). Among other important carbohydrates are hemicellu- 

 loses, which Pringsheim stated is a poorly defined collective name for 

 polysaccharides. A small amount of starch may be present in wood, 

 about 3 to 4 percent, or less; and a certain amount of sugar (Schorger). 

 Lignin is a noncarbohydrate incrustation substance in wood and makes up 

 from about 23 to 28 percent of its bulk (Pringsheim). There are also in 

 wood ash, less than one percent; proteins, a little under one percent, 

 according to Pringsheim, in fir, pine, oak, and beech; fats; waxes; resins; 

 and other substances. Straw and hay have about 30 to 35 percent cellu- 

 lose, about 20 to 30 percent lignin, 3 to 10 percent protein, and 20 to 

 30 percent starch. 



The animals that ingest these materials may use one or more of the 

 constituents, and that is not necessarily cellulose. The larva of the goat 

 moth Cossus cossus, though ingesting wood, does not affect the cellu- 

 lose (Ripper, 1930) . It has no cellulase and contains no symbiotic micro- 

 organisms. Ripper found that the carbohydrate used is supplied at least 

 in part by soluble sugars, perhaps also by hemicelluloses. Mansour and 

 Mansour-Bek (1934a) concluded that larvae of the cerambycid Xystro- 

 ceyca globosa, with no cellulase and no micro5rganisms, derive their 

 sustenance from the relatively high content of sugars and starch in the 

 wood attacked (10.4 percent) . Data bearing on the fact that some wood- 

 eating insects seem to make no use of cellulose, but depend on the 

 starch and sugars in the wood, being limited therefore to certain 

 kinds of wood rich in these substances, were discussed by Mansour and 

 Mansour-Bek (1934b). Ullmann (1932) stated that the carbohydrate 

 requirements of invertebrates are met chiefly by sugars and hemicellu- 

 loses. 



