362 
Dientamoeba fragilis 
Another free-living binucleate amoeba, “Atnoeha’’’ diploidea'^, has been 
described by Hartmann and Nagler (1908) and Nagler (1909). This 
organism again appears to us improperly placed m the genus Amoeba, 
on account of its nuclear arrangements and life-history. It also, we 
believe, will have to be placed in another genus, but one different from 
that occupied by “Amoeba” binucleata. Alexeieff (1912 b) proposes to 
place it in the genus Sajjpinia (Dangeard, 1896), a genus containing the 
species S. pedata, originally assigned to the Acrasiae. We believe that 
this proposal has much to recommend it, although it has been rejected 
by Cbatton (1912). When, however, Alexeieff proposes further to place 
“Amoeba” mira, described by Glaser (1912), in the same genus, we are 
not able to agree with him completely: for we cannot determine whether 
this name was given to a uninucleate or a binucleate form. It should be 
noted that “A.” binucleata and “A.” diploidea appear to divide in a some¬ 
what similar manner. In both, division of the two nuclei takes place before 
fission of the cytoplasm, so that the organisms—both young and old-— 
are always binucleate^. The genus Paramoeba was proposed by Scbaudinn 
(1896) for a marine amoeba possessing two “nuclear” structures; and 
some parasitic amoebae, originally described in Sagitta by Grassi, have 
recently been placed in the same genus by Janicki (1912). The latter 
amoebae appear to resemble, both as regards life-bistory and nuclear 
structure, the form described by Scbaudinn; but bis observations and 
also those of Janicki appear to us still problematic. In any case the 
organisms which they studied are forms possessing two nuclei—if they 
really are both nuclei—which are xinlike; and it is clear that our new 
amoeba cannot be placed in the genus Paramoeba^. 
The foregoing considerations will make it evident that the binucleate 
him in this, as we believe “Amoeba” binucleata should be placed in a genus different from 
that occupied by the type species of the genus Hartmannella (H. hyalina Dangeard). 
^ This organism was obtamed by Hartmann and Nagler in cultures from the faeces 
of lizards. We ourselves have found it on one occasion m a sample of human faeces, in 
which it made its appearance after the specimen had been kept in a glass tube for some 
days in the laboratory. 
2 Nagler (1909), however, notes the occasional occurrence of uninucleate individuals 
in “A.” diploidea —an observation which we are able to confirm from our own study of this 
organism. 
^ Some organisms found in the intestine of man have been placed in the genus 
Paramoeba by Craig (1906), and later in the genus Craigia by Calkins (1912). They have 
since been recognized by Barlow (1916). The forms described by these authors have 
nothing to do with the organism which we call Dientamoeba, nor can they be placed in 
the genus Paramoeba Scbaudinn. They are not binucleate amoebae, so far as we can deter¬ 
mine, and owe their existence, in our opinion, to errors of observation and interpretation. 
We regard “Craigia” as a non-existent organism and the genus as nomen nudum. 
