1084 PARASITES OF PROTOZOA 



occasions on Ephelota gemmipara and Acineta papillifera; and Chatton 

 and A. Lwoff (1924b) encountered it on Trichophrya salparum. In 

 Ephelota it attacks chiefly the region in which the stalk is attached to the 

 body. It sucks out plasma, and its presence leads to fragmentation of the 

 nucleus and degeneration of the whole cytoplasmic mass. The parasite 

 then detaches and swims to another suctorian. Hypoconia ascid'iarum 

 Collin was found on a tunicate, but probably actually is a parasite of 

 Trichophrya salparum, and may not be different specifically from H. 

 acinetarum (Chatton and A. Lwoff, 1924b). 



Ectozoic Suctor'ia. — In connection with the relationship between ex- 

 ternally attached Suctoria and their ciliophoran hosts, we must keep in 

 mind the fact that phoresy is widespread among Suctoria. Many forms 

 occur attached to other organisms, and often a species has been found 

 only on a particular host species. The host is not directly concerned in 

 the nutritive processes of the suctorian. Ciliophora may, like many Meta- 

 zoa, serve as hosts for these ectocommensals. Examples of such phoretic 

 forms are Ophryocephalus capitatum Wailes on species of Ephelota; 

 Urnula epistylidis Claparede and Lachmann on Epistylis and other Suc- 

 toria (see Gonnert, 1935); Tokophrya quadri partita (CI. and L.) on 

 Epistylis; Trichophrya epistylidis (CI. and L.); Metacineta mystacina 

 (Ehrbg. ) on Carchesium; and Tokophrya carchesii (CI. and L.) on 

 Car che Slum. Ectocommensalism in such attached forms may be obligatory 

 or facultative. 



Pseudogenima Collin is more closely adapted to an ectoparasitic man- 

 ner of life on other Suctoria. Reproduction is by internal embryos, and 

 fixation to the host is by a short, stout peduncle embedded in the cyto- 

 plasm. Tentacles are absent, and Collin (1912) considered it possible 

 that the fixation organelle has an absorptive function. Collin Hsted three 

 species: P. fraiponti Collin, 1909, on Acineta dirisa; P. pachystyla 

 Collin, 1912, on Acineta tuherosa; and P. keppeni Collin, 1912, on 

 Acineta papillifera. The last species is said to have a rounded form and 

 apparently no pedicle, and its location in its host is sometimes external 

 and sometimes almost entirely internal. Collin (1912) believed that it 

 furnishes a natural transition from Pseudogenima to Endosphaera. 



The species of Allantosoma occur in the intestine of the horse, an 

 endozoic habitat which is unique for Suctoria. According to Hsiung 

 (1928), the species A. dicorniger is strictly a lumen-dweller, and is 



