PROTOZOA AND OTHER ANIMALS 967 



wood, it is usually possible to obtain cellulose-digesting bacteria in cul- 

 ture from all regions of the alimentary canal, especially the fore-gut. 

 These disappear in time when roaches are fed on paper, and he believed 

 that they are forms living in the wood and accidentally ingested by 

 the insects. 



Numerous fungi were isolated by Hendee (1933) from wood in- 

 habited by Zootermopsis angustkollh, ReticuUtermes hesperus, and 

 Kalotermes minor. Dickman (1931) obtained cellulose-digesting or- 

 ganisms, both bacteria and molds, from material attacked by termites, 

 probably R. favipes and Zootermopsis sp. Cellulose-decomposing molds 

 were found by Hungate (1936) in burrows and pellets of Zootermop- 

 sis. He concluded, after analyses of sawdust acted on by external or- 

 ganisms and material that had passed through the termites (possibly 

 several times), that cellulose decomposition by bacteria and molds in 

 the wood of the colony is negligible in comparison with that digested 

 in the termites. That fungous action can render cellulose usable by 

 termites is shown, however, by an observation of Cleveland's (1924). 

 Termites deprived of Protozoa died soon on a cellulose diet, but lived 

 indefinitely when a cellulose-decomposing fungus accidentally developed 

 in certain vials. 



The flora of spirochetes and other bacteria in the gut of termites, and 

 this applies also to Termitidae, is considerable. They live free in the 

 lumen, attached to certain Protozoa, or attached to the lining of the 

 walls. Spirochetes do not grow on the usual laboratory media (Dick- 

 man, 1931). The possibility that they may participate in digestion of 

 cellulose and hemicellulose in termites was admitted by Cleveland 

 (1928a). In Cryptocercus, however, Cleveland killed the Protozoa, 

 leaving the spirochetes, by contrifuging; and cellulase disappeared in 

 twenty-four hours. The enzyme was not found after defaunated roaches 

 were reinfected with bacteria and spirochetes. 



Excepting certain castes and brief phases of development, all termites 

 except Termitidae have great numbers of flagellates in the hind-gut. 

 The vestibule, large intestine, and caecum become voluminous organs to 

 accommodate these symbionts. Hungate (1939) estimated that the gut 

 contents containing the Protozoa amount to from a seventh to a fourth 

 of the total weight of Zootermopsis angusticollis. Katzin and Kirby 

 (1939) found the gut contents to be about a third of the weight of 



