14 RESEARCH IN PROTOZOOLOGY 



Some forms are highly pathogenic (Hydrama:ba hydroxena) ; 

 others are relatively harmless and may benefit the host by keeping 

 the surface clear of dead epithelium and detritus {Kerona 

 pcdiculus) . 



There are two interesting protozoa belonging to the class sarco- 

 DiNA, order proteomyxa, that crawl over the surfaces of algae 

 and extract the cell contents through perforations which are 

 made in the cellulose wall. One of these, Vampyrclla lateritia 

 (Fresenius) Cienkowski, feeds primarily on Spirogyra; the other, 

 Pseudospora volvocis Cienkowski, feeds on Volvox. 



A fairly exhaustive search of the literature reveals twelve 

 genera and twenty-six species of protozoa parasitic on the external 

 surfaces of various animals; principally fishes, amphibia, flat- 

 worms and polyps. 



Class SARCODiNA, Order amcebida. 



Amoeba mucicola Chatton. 



Chatton (1909) described a new species of Amoeba, A. mucicola, 

 found on the gills of fish. Some of the infected animals died with 

 all signs of asphyxiation. There is a ciliate, Trichodina labrorum, 

 associated with the amoebae; it is possible that these infusoria aid 

 the amoebae by loosening up the epidermal cells of the host. 



Description: Size when at rest i2/i to 30/i in diameter; progression by 

 means of one or two large lobose pseudopods ; found associated with 

 Trichodina labrorum in the mucus on gills of fish; not proven to be an 

 habitual parasite. 



Hydramooba hydroxena (Entz) Reynolds and Looper. 



Entz (191 2) described an amoeba which he found in great 

 numbers, both on the outer surface and in the enteric cavity of 

 hydras collected from pools in the vicinity of Budapest. The in- 

 fected polyps showed signs of degeneration, but upon making a 

 study of the phenomenon Entz came to the conclusion that the 

 amoebae were not causing the trouble. Although he observed hydra 

 cells in the food vacuoles of the amoebae, he considered that their 

 principal food consisted of ciliates found in the enteron of Hydra. 

 He attempted to transfer the infection to other Hydra but these 

 efforts were not very successful. 



Wermel (1925) carefully studied the cytology of this form. In 

 general his findings regarding the morphology and biology of the 

 amoebae agree very closely with those of Entz. He states that in 



