ENTAMOEBA HISTOLYTICA 29 



author, to denote E. histolytica. Consequently it becomes a synonym 

 of the latter. Entamoeba nipponica Koidzumi (1909) almost certainly 

 included* E. histolytica and possibly also E. coli and other amoebae (?) 

 and tissue cells. Darling (1913), by misquotation, renamed it £. nippon- 

 ensis. E. hartmanni Prowazek (1912 rt) was certainly for the most part 

 E. histolytica — a strain producing small cysts. E. tenuis Kuenen and 

 Swellengrebel (1917) and E. ininittissima Brug (1917) are similar strains 

 of E. histolytica. Swellengrebel (1917) has described these small cysts as 

 belonging to the flagellate Chilomastix mesnili : Aragfto (191 2) has included 

 them with cysts of E. coli in his " E. brasiiicnsis" : Woodcock and 

 Penfold (1916) call them E. niinnta, though this is not the E. ininuta of 

 Elmassian (1909), which was the common strain with cysts about 12 /a 

 in diameter. Everybody will admit now that E. tetragena and E. africana 

 Hartmann (1907) are synonyms of E. histolvtica. Nevertheless, a word 

 may be said here about the former, as it has a curious and little known 

 history. 



From the papers of Huber (1903, 1906, 1909) it is clear that he re- 

 discovered the cysts of E. histolytica at about the time when Schaudinn 

 (1903) named this parasite and described its "spore-formation." Huber 

 showed the cysts to Schaudinn, who would not admit that they belonged 

 to E. histolytica : but he told Huber that they belonged to a different 

 species, which he had studied in one case himself, and which he was 

 going to call E. tetragena. By a misprint in the original version (Huber, 

 1906), this name is written " tetragona " — a mistakef which Huber (1909) 

 corrected later. When Viereck (1907) rediscovered the cysts, he tacitly 

 adopted Schaudinn's name, and followed him in regarding the species 

 as distinct from E. histolytica. However, he appears to have considered 

 that it was really a variety of £. coli, and proposed tetragena as a varietal 

 and not as a specific name. Hartmann (1908), after rediscovering 

 " E. africana," decided that it was identical with Viereck's species, and 

 named it E. tetragena Viereck — still supposing it to be a new species. 

 The muddle thus created by the German workers, as a result of ignoring 

 Huber's work and supporting Schaudinn's wrong observations and 

 interpretations, has survived in certain quarters to the present day. 

 E. tetragena and E. histolytica are names of the same organism, and there 

 is no justification whatever for employing the former. Nevertheless, 

 Kuenen and Swellengrebel (1913) and some other modern workers refuse 

 to give it up. A variant on the name (£. " tetragina ") was introduced 

 by Walker (191 1), through a mistake of some sort. The sooner all these 

 names — tetragena, tetragona, tetragina — are forgotten, the better will it 

 be for both zoology and medicine. 



It remains to add that the "amoeba" described by Noc (1909) from 

 cases of dysentery was partly E. histolytica. His forms from the stools, 

 containing red blood corpuscles, undoubtedly belonged to this species : 

 but the forms which he cultivated were just as certainly free-living 

 amoebae, and not E. histolytica. The "£. histolytica" which Lesage (1905) 

 cultivated from dysenteric stools, and with which he performed some 



• Some of the forms of " E. nipponica " are stated to have contained red blood 

 corpuscles. If these really were amoebae— and not endothelial cells— then they must 

 have been jE. histolytica. 



t At first sight this looks like a pun on Viereck's own name— but it seems to have 

 been unintentional. 



