74 THE AMOEBAE LIVING IN MAN 



I therefore conclude that Grassi's "Amoeba coli" was, for the most part, 

 Entamoeba coli; but that it inckided also, in all probability, some 

 individuals at least of E. histolytica. 



The next important work to be considered is that of Quincke and 

 Roos (1893) and Roos (1894), whose admirable work on E. histolytica 

 has already been noted. These observers also studied Entamoeba coli, 

 of which they gave an easily recognizable description and good figures. 

 They found the organism in the stools of a patient with colitis, and in 

 9 healthy human beings out of 24 whose stools they investigated. 

 Unfortunately, the clinical condition of the first case led them to believe 

 that his amoebae were a distinct species from the others, though they 

 found no morphological differences in either the amoebae or their 

 cysts to justify this conclusion. They named this "pathogenic" form 

 ''Amoeba coli mitis," and the form from healthy people "Amoeba 

 intestini vulgaris." From the descriptions and figures these amoebae 

 were identical, except as regards their provenance ; and both these names 

 were therefore given to the same species — namely, Entamoeba coli. 

 I would point out here again that the names which Quincke and Roos 

 gave to their amoebae should not be considered in discussing priority 

 in the nomenclature of these organisms. The names are trinominal 

 descriptive terms, and not binominal names bestowed in accordance 

 with the Rules of Nomenclature. They have no status and are not valid 

 zoological names. It is therefore not justifiable to attempt to revive 

 them, as Aragao has recently done. He proposes (1917) to replace the 

 name £. coli by " Eitdameba intestinivitlgaris" or (1917^) " Endamoeba 

 intestino-viilgaris Quinckt and Roos, 1893"; though these are not their 

 names at all, but Aragao's emendations which attempt to make one of 

 their designations of this organism conform to the Linnaean system — 

 a system which they did not follow. Aragao's names are thus synonyms 

 without validity. 



Quincke and Roos gave a good description of E. coli, and of the 

 characters which distinguish this species from E. liistolytica. They 

 describe the amoeba as sluggish, with no sharp demarcation between 

 ectoplasm and cndoplasm, with food-vacuoles containing many ingested 

 foreign bodies but never red corpuscles. The nucleus is also noted 

 and recognizably figured. The cysts are distinguished from those of 

 E. histolytica by their larger size (16 — 17 fi) and thicker walls, and are 

 said to contain one or more nuclei. On this point their description is 

 defective. They found further that this species is non-pathogenic to the 

 cat, and they did not succeed in infecting this animal either with cysts 

 per OS or with amoebae per anum : but Roos (1894) points out that man 

 probably acquires his infection by swallowing the cysts, in the same 

 way that the cat may become infected with E. histolytica — as their 

 experiments had proved. It is difficult to understand why these really 

 excellent observations should have had so little influence on later 

 workers. Their only real blemishes were errors in nomenclature and 

 insufficient investigation of cytological details. 



Soon after Quincke and Roos, Casagrandi and Barbagallo (1895, 

 1897) made important contributions to our knowledge of Entamoeba 

 coli. Unfortunately they contradicted the conclusions of the former 

 workers — without adequate evidence — and maintained that there is only 

 one species of intestinal amoeba in man. They maintained— with 

 Grassi — that this amoeba is harmless, and occurs in both dysenteric 



