248 C. CLIFFORD DOBELL. 
there are also present many blood-corpuscles and broken-up 
epithelium cells in the large intestine. These are readily 
ingested by the amcebee. But their presence may be due, as 
Neresheimer (40) believes, to the injurious action of the 
intestinal worms which are always present in greater or less 
numbers. 
All attempts to cultivate Hntamceba ranarum on 
Musgrave and Clegg’s medium have failed. 
Structure.—This amceba is remarkable for the ease with 
which its structure at all stages of development can be seen 
during life. For instance, the nucleus can, with proper 
illumination, etc., be seen in the living animal just as plainly 
as ina fixedand stained specimen. 
When an ordinary individual is examined in the living state 
it presents all the features usually seen in any amoeba (see 
fig. 52, Pl. 4). There is no sharply-marked differentiation 
into ectoplasm and endoplasm; there is no contractile 
vacuole; there are the usual food bodies present more or less 
plentifully ; but the most distinctive feature is the nucleus. 
By far the greater part of its chromatin is distributed at the 
periphery, so that in optical section the nucleus is always 
seen as a beaded ring (figs. 52, 53). Staining shows that a 
part of the chromatin is also distributed inside in the form of 
minute granules of varying size, arranged in a more or less 
distinct network (fig. 55). There is no caryosome (cf. 
Grassi). In fixed and stained animals the cytoplasm shows a 
very distinctly alveolar structure (cf. fig. 53, ete.). 
It is, of course, very difficult to give exact measurements 
of an organism suchas this. When more or less rounded the 
ordinary individuals measure about 20—30 jy in diameter. 
The nucleus is more easily measured. Its diameter is usually 
about 6 uw (cf. Grassi). 
Very much larger organisms are sometimes to be found 
(fig. 58). They are often stuffed with food to a most sur- 
prising extent, but are nevertheless very active. ‘The largest 
I have found measured over 60 u in length when in a very 
slightly extended condition. In these forms the nucleus 
