3o8 



PLASMODROMATA AND SARCODINA 



perate Zone. In the former it is especially common in the faeces of 

 natives. 



Pathogenicity.— £ . coli is a non-pathogenic commensal found in 

 man, and possibly in rats and mice, and perhaps in other animals. 

 Views as to its pathogenicity have probably arisen through mis- 

 taking the tetragena phase of L. histolytica for L. coli. An Amoeba 

 resembling L. coli is found in monkeys in which an Amoeba resem- 

 bling Z. histolytica, and called/., nuttalli, is also found. 



Loeschia histolytica Schaudinn, 1903. 



Synonyms.— coli Loesch, 1875; Entamceba histolytica 

 Schaudinn, 1903; Entamceba tetragena Viereck, 1907; E. africana 

 Hartmann and Prowazek, 1907; E. minuta Elmassian, 1909; and 

 Amoeba dy sentence Councilman and Lafleur, 1891. Among the 

 many doubtful species of Amoebae found in man there must be 

 many names which are synonyms of L. histolytica, but comparisons 

 are very difficult, as descriptions are often incomplete- — e.g., Amoeba 

 urogenitalis Baelz, and Amoeba pulmonalis Artault. 



Nomenclature.- — The correct name is Loeschia coli (Loesch, 1875), 

 as will be explained below. 



Definition.- — Loeschia with cytoplasm often containing red 

 corpuscles and with four-nucleate cysts. 



Historical — Early Observations.- — Loesch discovered the amoeba 

 which he named Amoeba coli in motions from a case of dysentery, 

 and considered it to be pathogenic. It was by this name that 

 Quinke and Roos in 1893 called the organisms found by them in 

 dysentery. As already stated. Councilman and Lafleur called an 

 amoeba found in cases of dysentery Amoeba dysentericB, and it is 

 certain that this was Loesch 's Amoeba coli. An amoeba somewhat 

 similar to the ' tetragena stage ' of L. histolytica was seen by Kruse 

 and Pasquale in 1893. 



We thus see that the- correct name for the dysenteric amoeba 

 is Loeschia coli, as Dobell has pointed out, and that the correct 

 name for the harmless amoeba is L. hominis, because Casagrandi 

 and Barbagallo called it Entamoeba hominis in 1897, when it really 

 had no name. Unfortunately Schaudinn did not utilize this name, 

 and in his revision applied the term ' coli ' to the non-pathogenic 

 form, and invented the name histolytica for the pathogenic amoeba, 

 which is difficult to change at the present time, as there is no 

 certainty that there is at present finality in this nomenclature. 



Differentiation.- — In 1902 Jiirgens for the first time clearly 

 differentiated the pathogenic amoeba, and in the following year 

 (1903) Schaudinn studied and compared the morphology and the 

 life-cycles of hisZ. coli and hisL. histolytica, and thus established 

 their characters, and gave the following account : — 



Morphology. — Its average measurement is 25 to 50 in diameter, and 

 therefore the average is greater than that oi L. coli. It consists of clear 

 hyaUne ectoplasm and granular endoplasm, in which can be seen red blood- 

 corpuscles, vacuoles, bacteria, and other matters, but the nucleus is not 



