16 PROF. E. A. MINCHIN ON PROTOZOAN (Jan. 12, 
described in quite general terms. It is seen that the nucleus is 
an ovoid or nearly spherical space limited by a delicate membrane. 
In the interior is a deeply staining karyosome, which may be 
spherical, ovoid, pear-shaped, or even dumbbell-shaped. The 
karyosome is always large, and sometimes so large as to nearly 
fill up the entire nuclear cavity and appears to be immediately 
surrounded by a clear space. The remainder of the nucleus is 
occupied by a faintly granular material, which, owing to the 
excentric position of the karyosome, forms usually a crescentic 
area on one side of the nucleus. In this area coarser dots of 
chromatin can be made out, especially in the neighbourhood of 
the nuclear membrane, which is probably composed also of chro- 
matin. No details of structure could be seen in the karyosome 
itself. 
The foregoing statements apply to the nuclear structure of the 
large or medium-sized forms, since I was not able, unfortunately, 
to find any of the small forms, always rare, in my preparations 
stained with 1ron-hematoxylin. 
The kinetonucleus appears as a rounded or ovoid mass in 
preparations stained by the Romanowsky method. It is larger, 
both absolutely and relatively, in the very small trypanosomes 
than inthe large. In preparations stained with iron-hematoxylin 
it appears either rod-shaped or rounded in form, but in either 
case very much smaller in size than it appears when stained by 
the Romanowsky method. If the hematoxylin be not much 
extracted, the kinetonucleus is often difficult to distinguish from 
the blepharoplast, the two together appearing to form a single 
mass of triangular or irregular outline. If, on the other hand, the 
extraction of the hematoxylin be carried too far, the blepharo- 
plast and flagellum become completely decolorized and the 
kinetonucleus appears as a very sharply defined and deeply 
stained body, im which no details of structure could be dis- 
tinguished. 
The flagellum arises from a distinct blepharoplast, which can 
almost always be seen clearly, and usually lies close beside the 
kinetonucleus. In some cases, however, the blepharoplast and 
kinetonucleus are separated by a considerable interval, and then 
appear to be connected by an ill-defined band of material staining 
more lightly (fig. 98). In the living condition also, as stated 
above, I observed in some cases two separate grains, which appa- 
rently represented the kinetonucleus and blepharoplast. 
The flagellum arises direct from the blepharoplast and runs 
along the edge of the undulating membrane in the usual way. 
As already stated, the free flagellum is short in the large stout 
forms, long in those of medium or small size. It is worthy of 
note that in the smaller forms the free flagellum ends distally in 
a distinct grain or dot. The undulating membrane is shallow, 
with many small pleats as a rule, in the stout forms with short 
free flagellum (fig. 13); but im all forms with a long free flagellum, 
