270 
The Life History of Amoebae 
of the ileum and not, as the others, from the colon) were not only 
more motile but much more resistant, which points to their natural 
habitat not being the colon but the ileum or possibly the jejunum. 
The cysts are very resistant outside the host. They remain alive 
in the faeces for more than a month; and are consequently much more 
resistant than the cysts of E. histolytica which only remain alive for a 
few days unless they are placed in clear water {cf. Kuenen and Swellen- 
grebel, 1913). When treated with Lugol’s solution or iodine, some 
cysts stain yellowish, others stain yellowish with a spherical red-brown 
mass in the interior. This brown sphere (figs. 34-36)»epresents a vacuole 
containing glycogen resembling similar glycogen-vacuoles within the 
cysts of E. coli and E. histolytica (as described by Kuenen and Swellen- 
grebel) and of E. chattoni and E. oris (Swellengrebel, 1914). These 
glycogen-vacuoles seem to be of common occurrence in intestinal 
amoebae. When the cysts are kept alive outside the body the glycogen- 
vacuoles gradually disappear within a week and at last all the cysts 
are without a vacuole (4-nucleate cysts). 
We did not succeed in cultivating this amoeba from stools containing 
many motile forms or cysts. 
Observation of fixed and stained freparations. Preparations fixed 
wet in corrosive alcohol and stained with iron haematoxylin showed 
the following forms; 
Amoebae (PI. II, figs. 10-17). They measure 4-8/x, • sometimes 
with distinct although narrow ectoplasm (fig. 10). The nucleus of the 
well-known Umax type generally lacks a distinct membrane, sometimes 
a granule can be made out in the centre of the karyosome (fig. 11). 
Nuclear division sets in by the karyosome assuming the dumb-bell 
shape (fig. 12) and subsequently dividing (fig. 13). Afterwards the 
vesicular part of the nucleus is equally divided, the two parts of the 
karyosome remaining linked together for some time by a chromatic 
filament (fig. 14). The disappearance of the latter marks the final 
stage of the nuclear division (figs. 15,16). Sometimes amoebae are found 
showing the karyosome in the form of a crescent or a rodlet, in this 
form it may divide, the parts being united by linin filaments (fig. 17). 
Probably these forms should not be considered as normal. 
Cysts. The younger stages are uninucleate with a distinct cyst 
wall and a large karyosome (fig. 18). They correspond to the cysts 
seen by James. In the next stage the vacuole appears which was 
shown to contain glycogen (fig. 19), the nucleus divides (fig. 20) and 
near the nuclei a few chromatic granules make their appearance, each 
