188 L. R. CLEVELAND. 



is of the opinion that some soil bacteria cause CH 4 fermentation 

 of cellulose and that others cause H 2 fermentation. McBeth 

 (1913) thinks cellulose-fermenting organisms are not responsible 

 for the production of gases. Gas, he thinks, is produced by con- 

 taminating organisms. 



Abstracting Klason's remarkable researches on lignin, Cross 

 and Doree (1922) state: ".Beto-lignin (C J9 HIS O 9 , and that part 

 of lignin precipitated by arylamine bases is designated as acro- 

 lein-lignin or alpha-ligmn. The other part, which is not precipi- 

 tated, appears to be a carboxyl group and is called carboxyl 

 lignin or fo/a-lignin) must therefore be bound to cellulose and 

 probably to a//>/?a-lignin (C 22 H 22 O 7 ). Lignin cannot well be 

 assumed as a secondary product derived from cellulose, but 

 appears as a direct assimilation product of CO 2 and H 2 O or for- 

 maldehyde. Therefore the formation of lignin is a function of 

 chlorophyll." Klason thinks lignin is possibly present in wood 

 as a glucoside and that it may be built up from pentose. 



THE RELATION OF THE PROTOZOA TO THEIR HOST. 



A. HISTORICAL. 



i. True Parasites. 



Most students of termites, and termite protozoa, have focused 

 their attention on the morphology 1 and behavior of either the 

 termites or the protozoa which they harbor; consequently, the 

 interrelation of host and parasite has been very little investigated. 



Grassi is really the only investigator who has not confined his 

 attention almost exclusively to a study of either the termites or 

 their intestinal protozoa. He has studied the termites and the 

 protozoa, but has never carefully investigated their relationship. 

 His work on the two groups of organisms, termites and termite 

 protozoa, has been largely a study of two separate and distinct 

 problems; namely, the morphology and systematics of the pro- 

 tozoa, and the physiology and behavior of the termites, with 

 special emphasis on the underlying factors in caste production. 



Grassi and Sandias (1893) think that the relative abundance 

 of protozoa present in the various adult individuals in a termite 



1 The morphology of termite protozoa is a fascinating subject and occupied the 

 writer's entire attention for a year before the present investigation began. He will 

 publish in a later paper a description of several new forms. 



