THE PROTOZOA OF TERMITES 33 



to exist in dose symbiotic partnership with their host, so that the 

 termite is unable to survive upon the usual cellulose diet without 

 them. 



Infection by other protozoa — ciliates, sporozoa and amoebae — is 

 not at all comparable in abundance to the flagellate infections. The 

 only ciliate definitely known to occur in termites, Nyctothenis, has 

 been found only in a few individuals of certain species. Some 

 gregarines and microsporidia are also known, and these are just 

 as sporadic in their occurrence. Amoebae have not been found in 

 any termites in which the crowded faunas of flagellates occur, 

 but an abundant infection with large forms is characteristic of 

 at least two species of the genus Mirotennes in the termitid^. 

 Small numbers of minute amoebae and trichomonad flagellates have 

 been found in certain other termitid^. 



Cleveland (1925c) has investigated the occurrence of flagellates 

 in the various casts of Reticulitermes iiavipes. He found that 

 when wood is eaten protozoa are always present, but when wood 

 is not taken into the digestive tract these are absent. The repro- 

 ductive forms lose their protozoa after they give up a diet of wood 

 and are supported by salivary secretions from the workers. The 

 adult soldiers, which contain protozoa, are unable to chew wood, 

 but obtain partly digested proctodaeal food from the xylophagous 

 members of the colony. At the time of molting, all individuals of 

 the colony lose their protozoa. Rarely a portion of the cast exo- 

 skeleton is eaten before the protozoa, discarded with the intes- 

 tinal lining, are all dead, but generally the molted termites do not 

 become reinfected if isolated. Reinfection is soon accomplished 

 upon contact with nomially faunated individuals. 



DISTRIBUTION 



A distributional list recently compiled by Emerson (1928) ac- 

 counted for 1503 species of termites in 131 genera. With respect 

 to intestinal protozoa, these termites may be divided into two large 

 groups, one usually with and one for the most part without in- 

 fection. The former group, made up of the three most primi- 

 tive of the four families, the mastotermitid^, kalotermitid.e 

 and RHiNOTERMiTiD^, includcs 382 species in thirty-four genera. 

 Of these, every species so far explored has its characteristic 

 flagellate fauna. About no species in forty-four genera of flagel- 

 lates have been described from less than fifty of the 382 termites. 



