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Entamoeba histolytica and E. ranarum 
others harmless. It is to Schaudinn’s credit that he recognized that 
there were really two different species confounded with one another— 
one harmless, the other pathogenic. As both had received the same 
name at different times, he therefore proposed to restrict the specific 
name coli to the one, while introducing a new specific name ( histolytica ) 
for the other, and simultaneously referring both to the genus Entamoeba. 
In principle Schaudinn acted strictly in accordance with the Rules of 
Nomenclature. But most unfortunately he assigned the name E. coli 
to the harmless amoeba, and introduced the new name E. histolytica 
for the pathogenic form. If he had studied the question more carefully, 
he would have discovered that Losch’s “ Amoeba coli''’ was the very 
form for which he proposed the name E. histolytica. It is impossible, 
I believe, for anybody to read LbsctTs very careful account of his 
amoebae, supported as it is by his post-mortem findings and illustrations, 
and reach any other conclusion 1 . Whatever confusion may have been 
introduced by subsequent writeis, there is no evidence at all that Losch 
studied more than one species, or that he confused two together: and 
there is no real doubt as to which that species was. It was the species 
which causes dysentery, and which Schaudinn renamed E. histolytica. 
The correct name of this organism is, therefore, according to the Rules 
of Nomenclature, Entamoeba coli Losch; and the name E. histolytica 
is a synonym without validity. 
It is to be noted that Schaudinn was completely unjustified in his 
revision of the name “ Amoeba coli.” Not only should he have retained 
the name coli for the pathogenic species, but he should also have re¬ 
frained from introducing any new specific names at all. The harmless 
amoeba, which he wrongly called “ E. coli,” had already not only been 
observed and recognizably described by Casagrandi and Barbagallo 
(1895), but also named by them (in 1897) Entamoeba hominis. Accord¬ 
ingly, this is probably the “ correct” name of the organism now generallv 
known as “A. coli.” 
Now although the name E. coli can claim priority over all others as 
that of the dysentery amoeba, the name E. dysenteriae clearly has no 
such claim. This name (“ Amoeba dysenteriae”) was proposed by 
Councilman and Lafleur in 1891 for the very same organism as that to 
which Losch gave the name “Amoeba coli 2 ” They proposed to change 
1 This appears to be the opinion also of Brumpt (1913), Wenyon (1915), Mathis and 
Mercier (1916), and others. 
2 “We have called the organism, which was first described by Losch under the name of 
amoeba coli, the ‘amoeba dysenteriae.’ The name given to it by Losch is not distinctive.’’ 
(Councilman and Lafleur. 1891, p. 405.) 
