Termites are divided into two types, the lower termite, which possesses symbiotic protozoa and several species of bacteria in the intestine and the higher termite, which has no protozoa but several species of symbiotic bacteria in the intestine. The digestive system for cellulose differs in each. In the higher termites, the digestive system is complex, since several problems remain unresolved. In the lower termites, cellulose digestion depends on the intestinal protozoa and symbiotic relationships between the termite and its intestinal protozoa, first published by Cleveland in 1924 (xcCleveland, 1924A). Recent reports, however, show that the symbiotic relationship in the digestive system involving cellulose is more complex. xcYamaoka and Nagatani (1975) reported that the termites themselves produce a cellulase which differs from the cellulase produced by the intestinal protozoa. Since the concept of the cellulose digestion system has changed significantly, the role of intestinal bacteria and their diversity in termites are presented here. [ABSTRACT FROM AUTHOR]