PARASITES OF PROTOZOA 1085 



not attached to any other organism. The other two species have certain 

 relationships to cihates, but apparently that is only occasional. Hsiung 

 wrote of A. intestmaUs that some were attached to Cycloposthiuni bipal- 

 matmu and Blepharocorys curvigula; Gassovsky (1919) recorded the 

 species as occurring in the colon, rarely the caecum, of horses, without 

 mention of any attachment to ciliates. A. hrevicornigev, Hsiung states, 

 is "often found attached to the body of the ciliate Paraisotrkha colpoidea 

 by one tentacle." Apparently these Suctoria prey upon the ciliates, but 

 are not constantly attached, as obligatory ectoparasites would be. 



The only account of a suctorian clearly ectoparasitic on Euciliata is 

 Chatton and A. Lwoff' s (1927) description of Pottsia mjusoriortim. The 

 chief host is Follkulhia ampulla, but it has been found also on Cothurnia 

 socialis. The parasites may occur in numbers on the body of Folliculina, 

 within the lorica. There are four tentacles at one end, on the surface in 

 contact with the host, prolonged rather deeply into the body of the host. 

 Embryos develop endogenously, swim actively, and become fixed to the 

 body of Follkulina. On different occasions, from none to 75 percent 

 of the heterotrichs have been found parasitized with as many as twenty- 

 two parasites. When the number of Pottsia is large, the host undergoes 

 degeneration. The parasites may survive for a time among the remains, 

 but eventually themselves disintegrate. 



Tachyblaston ephelotensis, as described by Martin (1909), has a 

 curious life cycle, involving both an external phoretic existence with 

 multiplication, and an intracytoplasmic parasitism, also with multiplica- 

 tion. It seems not impossible that reinvestigation will show that 

 two organisms have been confused in this cycle, since it is so unlike 

 the life histories of other Suctoria. The intracellular phases occur as 

 rounded bodies in Ephelota gemimpara. There is equal division, fol- 

 lowed by the formation of buds. Ciliated "spores" escape from the host 

 and after a brief period of existence become attached to the stalk of 

 Ephelota, developing a stalked lorica. The fixed form undergoes rapid 

 budding. Each bud is provided with a single tentacle, with the aid of 

 which, together with "euglenoid changes of shape," the bud travels up 

 the stalk to penetrate into the body of Ephelota. The internal parasitic 

 phase destroys the cytoplasm of the host. 



Endozok Suctoria. — The Suctoria that occur as internal parasites of 

 other Ciliophora, and have a wide variety of hosts, belong to the genera 



