134 



THE AMOEBAE 



The Commission, which had no protozo- 

 ologists among its members, went beyond 

 this, and decided that £^^/rt»/0(;^/>f/ was a 

 synonym of EiidcDiiueba and that both pro- 

 tozoa belonged to the same genus. Altho 

 the latter is obviously not true, this dic- 

 tum was accepted by many protozoologists. 

 Finally, after much agitation and several 

 long, involved papers by various author- 

 ities, the International Commission finally 

 reversed itself, and Enlanioeha is now 

 universally recognized as the correct 

 name for the species occurring in verte- 

 brates. 



The nomenclature and taxonomy of the 

 species of Eiitamoeha are about as con- 

 fused as it is possible to make them. 

 Some of the problems are explained below, 

 but puzzle addicts are referred to the 

 cited papers for the details. 



Members of the genus found in domes- 

 tic animals and man can be divided into 4 

 groups on the basis of trophozoite and 

 cyst morphology. A fifth group includes 

 species about which insufficient morpho- 

 logical information is available to deter- 

 mine which of the other groups they belong 

 in. Most of the species within each group 

 are morphologically indistinguishable; 

 they are differentiated on the basis of size, 

 hosts, pathogenicity, etc. Criteria of 

 this type are given different weights by 

 different taxonomists, and this fact com- 

 bined with a lack of cross-transmission 

 studies for many species accounts for 

 some of the confusion. More is due to 

 the fact that the original descriptions of 

 some of the species were so poor as to 

 make it difficult or impossible to be sure 

 what forms the authors were dealing with. 



The groups of Entamoeba will be des- 

 cribed first, and then the individual spe- 

 cies. 



1. fflSTOLYTICA GROUP. The nucleus 

 has a small, central endosome, a 

 ring of small peripheral granules and 

 a few scattered chromatin granules 

 between them. The cysts have 4 nuclei 

 when mature, and their chromatoid 

 bodies are rods with rounded ends. 

 Glycogen vacuoles, when present in 



the cyst, are usually diffuse and ill- 

 defined. 



Entamoeba histolytica of man, other 

 primates, the dog, cat and rarely 

 the pig. 



E)itai)ioeba harliuauiii of man and pre- 

 sumably also of the other hosts of 

 E. histolytica. 



Entamoeba eqni of the horse. 



Entanioeba anal is of the duck. 



Entamoeba moshkovskii of sewage. 



2. COLI GROUP. The nucleus has a 

 somewhat larger, eccentric endosome 

 than that of the histolytica group and 

 has a ring of coarse peripheral gran- 

 ules and some scattered chromatin 

 granules between them. The cysts 

 have 8 nuclei when mature, and their 

 chromatoid bodies are splinter-like. 

 Glycogen vacuoles, when present in 

 the cyst, may be fairly well defined. 



Entamoeba coli of man, other pri- 

 mates, the dog and possibly the pig. 



Entamoeba wenyoni of the goat. 



E)itamoeba nniris of mice, rats, ham- 

 sters, and other rodents. 



Entamoeba caviae of the guinea pig. 



Entamoeba cunicnli of rabbits. 



Entamoeba galli)iaynm of the chicken, 

 turkey, guinea fowl, duck, and goose. 



3. BO VIS GROUP. The endosome of the 

 nucleus varies in size; it may be as 

 small as that of the histolytica group, 

 but is generally larger than that of the 

 coli group. The ring of peripheral 

 granules in the nucleus may be fine or 

 coarse, evenly or irregularly distrib- 

 uted. Periendosomal granules may be 

 present. The cysts have 1 nucleus 

 when mature, and their chromatoid 

 bodies are either rods with rounded 

 ends or less often splinter-like. Gly- 

 cogen granules, when present in the 

 cyst, are usually fairly well defined. 



Entamoeba bovis of cattle. 

 Entamoeba ovis of sheep and goats. 

 Entamoeba dilimani of goats. 

 Entanioeba siiis of the pig and perhaps 



man. 

 Entamoeba bubalis of the carabao. 

 E)ita»ioeba cliattoni of monkeys and 



probably man. 



