PROTOZOA AND OTHER ANIMALS 911 



seems to be a similarity in type of Sphonucleus to H. rostrata (?), as 

 figured by Wenrich ( 1935 ) from the outside of a dead fresh-water snail. 

 At least until a systematic review of the whole group of Hexamita-Wko. 

 forms is made, it appears to be necessary, for the sake of clarity, to use 

 only the one genus name. 



The endozoic species of Hexamita are many and are found in a wide 

 variety of hosts. Though given species are restricted to single or related 

 hosts, the tendency to give different names to those in different hosts, 

 without adequate comparison with other described species, has been 

 manifest. 



Certes (1882) found Hexamita frequently in the stomach of oysters 

 from certain localities on the coast of France. Though he considered 

 this to be H. itjflata. he regarded it as a normal, reproducing inhabitant 

 of the stomach; and the identification is in no way positive. In other 

 invertebrates, Hexamita has been recorded from the reproductive organs 

 of the trematode Deropristis inflata in marine eels, but not in the in- 

 testine of the eel (Hunninen and Wichterman, 1936); from the cock- 

 roaches Blatta orientalis (Bishop, 1933), Periplaneta americana, and 

 Cryptocercus punctulatus (Cleveland, 1934); from the horse-leech 

 Haemopis sanguisugae (Bishop, 1932, 1933); from the milliped Spiro- 

 holus marginatus (Wenrich, 1935); from the larvae of Tipula (Mac- 

 kinnon, 1912; Geiman, 1932); and from Tubifex (Ryckeghem, 1928). 



These all occur in the gut, except for the trematode form, as noted, 

 and the one in Tubifex. The latter, furthermore, is the only one in in- 

 vertebrates to which probable pathogenicity has been ascribed. Hexamita 

 tubifci was encountered at intervals in the course of fifteen years in the 

 body cavity of Tubifex kept in culture in the laboratory in Louvain. 

 Worms that lost their power of activity, appeared whitish, and died 

 were found to have a more or less intense infection with Hexamita. 

 Ryckeghem considered the question as to whether the flagellate is a 

 parasite or a free-living form invading decomposing tissue. He con- 

 cluded that the former relationship exists, for he found it in living 

 worms in apparently healthy tissue, decomposing chironomid larvae 

 were not invaded by the flagellate, and it was encountered in different 

 collections at long intervals. Each time it was a source of trouble. 



Hexamita species occur in vertebrates of all classes. Fry and young 

 fingerlings of trout and salmon in hatcheries in the United States were 

 found by Moore (1922, 1923a, 1923b, 1924) and Davis (1923, 1926) 



