30 THE AMOEBAE LIVING IN MAN 



incredible experiments on cats (Lesage, 1907 a), were similar free-living 

 forms. The "Amoeba II " of McCarrison (1909), regarded by him as 

 possibly E. histolytica, was clearly in reality a cell and not an amoeba. 

 The "non-pathogenic Entamoeba tetragena" of Shimura (1916, 1918) is, 

 apparently, chiefly E. histolytica from healthy carriers. The " E. coli " 

 of Werner (1912) apparently included E. histolytica also — to judge from 

 his figs. 32-38, PI. II. And it is not improbable that the smallest 

 amoebae of " £. willianisi" described by Prowazek (1911, fig. 19) were 

 the precystic amoebae belonging to a strain of E. histolytica which forms 

 small cysts. But it would take too long to note all the names given to 

 E. histolytica by numerous authors who have casually included a few 

 individuals or cysts of this species in their descriptions or figures of 

 others. Specially noteworthy instances will be mentioned later. 



There are still two groups of amoebae which have to be taken into 

 account in discussing the nomenclature of E. histolytica; namely, the 

 amoebae found in human urine, and those found in the intestines of 

 various animals — especially dogs and monkeys. These will be considered 

 later (see p. 125 et seq.), as they cannot be conveniently discussed here r 

 but I will forestall the conclusions there reached by noting at this point 

 that I find sufficient justification for the inclusion of the names "Amoeba 

 urogenitalis " Baelz (1883), Amoeba vaginalis Blanchard (1885), and 

 Entamoeba venaticum Darling (1915), in the list of synonyms of E. his- 

 tolytica. On the other hand, I find as yet insufficient evidence for the 

 inclusion of any of the names given to the amoebae of monkeys. 



Entamoebae in many ways closely similar to E. histolytica have also 

 been found in several other animals. These, too, have been named, and 

 the synonymy of the dysentery amoeba cannot be completed without 

 taking them into account. 



Entamoeba ranarnm (Grassi) Dobell occurs in frogs and toads (cf. 

 my papers 1908, 1909, 1909 «). It resembles E. histolytica so closely in 

 certain ways as to suggest that it may be the same species. The precystic 

 amoebae and the cysts of the two forms are sometimes indistinguishable. 

 Their identity was suggested by Alexeieff (1914), and appeared to merit 

 further inquiry. Experiments which I made in 1916 seem, however, to 

 show clearly that E. histolytica and E. ranarnm are distinct species. At 

 all events, it was found impossible to infect tadpoles with the cysts 

 of E. histolytica. {Vide Dobell, 1918.) Another amoeba whose cysts 

 closely resemble those of E. histolytica is E. anlastomi Noller (1912), 

 which lives in the hind-gut of a leech,* Anlastomnm gulo Moq.-Tandon 

 (= Haemopis sangnisuga L.). At present there is no proof that this 

 amoeba is not identical with E. histolytica or E. ranarum, though it will 

 probably, I think, turn out to be a distinct species. 



Conclusions regarding Nomenclature of the Dysentery Amoeba. 



The conclusions which I draw from the facts noted in the foregoing 

 paragraphs may be summed up briefly as follows : 



The name used for the dysentery amoeba of man should be 

 Entamoeba histolytica Schaudinn, 1903, as this is the first zoo- 

 logical name correctly given to this species, and the only one 



* Not ot "the eagle," as Craig (i9i3<5, 1914, 1917) states — apparently as a result 

 of mistranslation of the German word " Egel." 



