STUDY OF PATHOGENIC AM(E BiE FROM BOMBAY. 117 
nucleus of the amoebae found in the sections was very scanty, 
and confined for the most part to the periphery of the nucleus. 
These observations are in accord with those of Noc, who, 
when writing of the amoebae which he isolated in culture and 
comparing them with Schaudinn’s E. histolytica, and living 
forms isolated from the walls of a liver-abscess, points out 
that the cultural amoebae were always smaller and contained 
more chromatin in the nucleus than those found in the tissues 
of a liver-abscess or of a dysenteric ulcer. How far these 
differences can be accounted for by differences in the methods 
of fixation and by the nature of the medium in which the 
amoebae have respectively developed it is difficult to say, 
yet it is evident that the amoebae which grow in cultures 
differ markedly in morphological characters from those found 
in sections of diseased intestine. Further study with fresh 
pathological material seems to be necessary before any 
definite conclusion can be arrived at as to whether the 
amoebae obtained in cultures are the true cause of dysentery. 
A few more details of the development of the amoebae in 
cultures remain to be mentioned. The following observations 
concern particularly the large amoebae of the liver-abscess, 
which was studied in greater detail than the smaller amoebae. 
A single amoeba has frequently been watched as it became 
encysted. Coming to rest the amoeba gradually shrinks and 
becomes condensed. During this period' the contractile 
vacuole beats more and more slowly; finally, having attained 
often an unusually large size, it very slowly shrinks and dis- 
appears. Other vacuoles in the protoplasm also disappear. 
Then a cyst-wall develops around the amoeba. A single 
nucleus is alone visible within the cyst as long as it remains 
transparent and its contents can be stained. 
When cysts formed in this way are planted on fresh 
medium the first change that is noticed is a gradual swelling 
of the cyst and the development of an increasingly large 
vacuole within it. The cyst-wall soon ruptures at some indefi- 
nite point and a single amoeba slowly flows out through the 
breach. 
