906 PROTOZOA AND OTHER ANIMALS 



Because of the presence of a red stigma and bifurcation of the root of 

 the flagellum, Hall assigned this flagellate to the genus Euglena, al- 

 though it is colorless, naming it E. leucops. 



Nieschulz (1922) examined large numbers of the fresh-water nema- 

 tode Trilobus gracilis, in the hope of finding Herpetonjonas (= Lepto- 

 monas) hiltschlii. This was not found, but he reported Astasia from 

 some specimens, usually only one or two in a host. There was no stigma 

 and no flagellum. He did not state in what part of the body the parasites 

 occurred. 



In the rotifer Hydatina senta. Astasia has been reported on three occa- 

 sions. Leydig (1857) observed it in the alimentary tract of almost all of 

 the hundreds of rotifers that were examined. Metabolic movements were 

 very active, a red stigma was present, and no flagellum was mentioned. 

 Hudson and Gosse (1889) wrote: "H. serita, too, suffers from an in- 

 ternal parasite. It . . . swims up and down its host's stomach by jerking 

 the contents of its body constantly backwards and forwards." Their fig- 

 ures show no flagella, and one, in color, shows a red stigma. Valkanov 

 (1928), without reference to other observers, named the organism he 

 found parasitic in the intestine of the same species of rotifer, A. hy- 

 datinae. 



In the intestine of gastrotrichs, Astasia-Uke inquilines were reported 

 by Voigt (1904). He found them in some specimens of a gastrotrich 

 that he later (1909) named Chaetonotus ploenensis, and was unable, 

 despite careful search, to find free-living examples of Astasia in the 

 material. Remane (1936, p. 231) stated that he found the same species 

 in the intestine of another species of Chaetonotus. 



Astasia doridis was found by Zerling (1933) to be rather abundant 

 in some eggs of the tgg masses of the nudibranch Doris tuherculatus at 

 Wimeraux. When heavily parasitized, larvae were destroyed. The para- 

 sites lacked flagella and stigmas and showed intense euglenoid activity. 

 Freed from the eggs, they lived many days with no change in morphology 

 and behavior. The flagellate was not found in the genital tract of the 

 adult. Zerling believed it probable, nevertheless, that adult molluscs are 

 infected by the parasites liberated into sea water at the hatching of in- 

 fected larvae, and that they transmit the parasites to their egg masses. 

 This is the only published record of a euglenid parasite in a marine host. 



Codreanu and Codreanu (1928) found a considerable percentage of 



