916 PROTOZOA AND OTHER ANIMALS 



digitijormis, which was described by Fabre-Domergue (1885) in mucus 

 on the body of Asterias glacialis, multiplying abundantly on damaged 

 and disintegrating starfish, but disappearing with death of the host. 



The genus Ophryoglena comprises large holotrichous ciliates of which 

 some species are free-living and others endozoic. Kahl (1931) listed 

 eleven of the former and five of the latter. Within the genus there is a 

 range from free-living habits, often with predatism, through commensal- 

 ism to strict parasitism in close relationship to the developmental cycle 

 of the host. 



The free-living species O. flava, according to Penard (1922), is vo- 

 racious and usually preys upon animals larger than itself, including 

 rotifers, small worms, and small Crustacea, especially Cyclops. It passes 

 under the carapace of Cyclops and consumes the living animal, the soft 

 parts of which are converted into food balls in the cytoplasm. 



Ophryoglena maligna, described by Penard (1922), preys upon O. 

 flava as a parasite. It invades the cytoplasm, in which the number is one 

 to four or more, and devours the host little by little until it is empty. 

 The ciliates were also found free in the water, but Penard believed that 

 before long they would attach themselves to O. flava. 



The three species that have been found in the intestine of Turbellaria 

 appear to be commensals. These are O. parasitica, reported by Andre 

 (1909) from 11 of 234 Dendrocoelum lacteum; O. pyriformis found 

 infrequently by Rossolimo (1926) in Sorocoelis maculosa and Planaria 

 nigrofasciata at Lake Baikal; and O. intestinalis from a large turbellarian 

 of the genus Dicotylus at Lake Baikal. It was shown that the last two 

 species cannot survive long in the water. 



Truly parasitic, however, are the species reported by Lichtenstein 

 (1921) and Codreanu (1930, 1934) from May-fly naiads. The former 

 found the parasites in the schizocoele and gonads of Baetis sp. near 

 Montpellier; the latter in five Ephemerida from the Alps and the Car- 

 pathians. Codreanu believed that parasitism by these ciliates may occur 

 widely in Ephemeroptera. In young Rithrogena the ciliates occur as cysts, 

 division taking place within the cyst, but in Baetis they are not encysted 

 at any time. When the reproductive organs develop in the females, most 

 or all of the ciliates invade the ovaries, the contents of which they ulti- 

 mately destroy. The May flies nevertheless become adults and in the act 

 of what would normally be egg-laying, ciliates are deposited in the water 



