1076 PARASITES OF PROTOZOA 



of general host-parasite relationships, it seems to the writer unlikely 

 that the same amoeba both parasitizes opalinids and lives in the in- 

 testinal lumen; certainly, to date, there is no proof of either possibility. 



Published reports seem to indicate a greater prevalence of entamoebae 

 in Zelleriella than in other Opalinidae, but they have been found also in 

 Protoopalina, Cepedea, and Opalina (Chen and Stabler, 1936). The 

 geographical distribution of the amphibian hosts of parasitized Opa- 

 linidae has been found to be very wide, but Chen and Stabler stated that 

 "only certain species of anurans and a certain percentage of individuals 

 of a given species harbor the parasitized opalinids." In a given host, the 

 percentage of ciliates containing hyperparasites varies greatly from none 

 to quite all, as noted by Carini (1933) and Brumpt and Lavier (1936) 

 in Zelleriella of Paludicola sigmfera, and by Chen and Stabler (1936) 

 in Zelleriella of Bufo marinus. The number of amoebae in a ciliate 

 ranges from one or very few up to a condition in which the cytoplasm 

 of the host is almost completely filled, more than a hundred being 

 present. They have been found mainly in the trophozoites, but may 

 occur also in precystic and encysted ciliates, according to Chen and 

 Stabler (1936), though Brumpt and Lavier (1936) stated that they had 

 never found them in the cysts. Chen and Stabler pointed out the im- 

 portance of the parasite in cysts, in establishing infections in a new 

 generation of the hosts. 



In opalinids, entamoebae occur either as vegetative forms or as cysts. 

 Stabler and Chen (1936) stated that they apparently feed on the endo- 

 spherules, and they observed instances of mitotic division. It has been 

 noted (Stabler, 1933; Carini and Reichenow, 1935; Stabler and Chen, 

 1936) that the cysts in the ciliates are all uninucleate; the same observers 

 reported binucleate and quadrinucleate cysts outside of the hosts. It 

 seems, in general, that all the parasites in one ciliate are in the same 

 stage of development; but Brumpt and Lavier (1936) gave an uncon- 

 vincing figure of a Zelleriella said to contain a uninucleate and a bi- 

 nucleate vegetative form, a precystic form, and a uninucleate cyst. 

 Furthermore, in their statement that certain cysts contain two or four 

 nuclei, though most are uninucleate, it is not clear whether or not they 

 found multinucleate cysts in the opalinid host. 



It has been noted that the parasites seem to have no injurious effect on 

 the host. The fact that parasitized ciliates may yet undergo normal divi- 



