17,4 Chatterjee: An Atypical Ameba 387 
There was marked variation in the size of the amcebee, the 
predominant range being from 16 » to 20 ». Many measured 
from 30 » to 40 ». A few were as small as 8 p. As remarked 
before, the nucleus was not at all of the histolytica type. In 
most cases, it was oval and quite unlike the circular ring of the 
histolytica nucleus. Plate 1, figs. 1 and 5, show the type of 
nucleus I found in most cases. It is sometimes rounded (Plate 
1, fig. 7). It is situated eccentrically as in Entameba histoly- 
tica. There is no differentiation into central and peripheral 
chromatin. No karyosome is seen. The nucleus stains uni- 
formly dark, and, in some cases, an elongated, unstained patch 
is seen near the periphery of the nucleus (Plate 1, fig. 6), but 
in most of the specimens the chromatin and the plastin form 
a uniformly stained mass. The nuclear membrane is not easily 
distinguished. In fact, the nucleus is of the “limax” type. It 
differs from it in not being so dense. It differs from the 
nucleus of the trophozoite of Entameba nana as described by 
Wenyon and O’Connor(7) and by Kofoid, Kornhauser, and 
Swezy(4) in that the chromatin substance is not clumped to- 
gether at one point on the nuclear membrane leaving the re- 
mainder of the nucleus clear. In some of the larger specimens 
(those measuring 32 » to 40 ») the nucleus showed evidence 
of division by mitosis. Even in division, no separation between 
peripheral and central layers of chromatin could be distin- 
guished, the entire nucleus being stained uniformly. 
In the structure of the cytoplasm this ameba shows well- 
marked, distinctive characters apart from that of Entameba his- 
tolytica. In the former there is a striking distinction between 
the ectoplasm and the endoplasm. Now, this very character is 
one of the points of distinction between Entameba histolytica 
and EF. coli; but by comparing Entameba histolytica with the 
amoeba under consideration, it will be found that the differen- 
tiation between ectoplasm and endoplasm is much more pro- 
nounced in the new ameeba than it is in E. histolytica. In the 
resting condition of the latter, no noticeable distinction between 
endoplasm and ectoplasm can be made out, but this is not the 
case with this ameba. Even in the resting condition a clear, 
glistening ectoplasm is seen surrounding the stained endoplasm. 
In the moving specimen during pseudopodium formation this 
distinction is much more pronounced (Plate 1, fig. 10). The 
structure of the endoplasm is alveolar in most cases ; in a few 
vacuolation is found (Plate 1, figs. 6 and 8). In a few indi- 
viduals ‘red blood corpuscles and, in some instances, bacteria 
