ECTOPARASITIC PROTOZOA 



15 



the neighborhood of jMoscow about ninety per cent of all the 

 hydras are infected. 



Reynolds and Looper (1928) conducted a series of experiments 



Fig. 2. — Hydramocba hydroxena. A, Living amoeba containing two con- 

 tractile vacuoles, nucleus and many food particles. B, Hydra during early 

 stage of infection showing four amoebae on tentacles and one on body. C, 

 Hydra during late stage of infection, note lack of tentacles and that the 

 amoebae practically cover the surface. D, generalized diagram of optical sec- 

 tion through nucleus. E, abrasion of Hydra's ectodermal surface by an 

 amoeba. F, amoeba ingesting endodermal cells of Hydra. A X about 150; B X 

 21 ; C X 42; D X about 800; E and F X 210. (A after Entz; all others after 

 Reynolds and Looper.) 



designed to show whether or not the amoebae were pathogenic to 

 their host. They concluded that the amoebse fed primarily on their 

 host's cells. Four amoebse with their progeny may cause death in 



