THE STRUCTURE OF TRYPANOSOMA LEWISI. 795 
appear to be correlated with any other structural variations 
of the trypanosome. 
By their reactions to the stains mentioned, the chromatoid 
grains are evidently allied to the chromatin-elements of the 
nuclei; they are stained in a manner similar to the tropho- 
nucleus by hematoxylin, gentian-violet, safranin, methylene- 
blue, and neutral red (in ‘T'wort’s stain). The Romanowsky 
stain alone fails to differentiate them clearly, but I have said 
enough already in support of my opinion that this stain is 
quite unreliable as a test for nuclear structures. Comparing 
the chromatoid grains with the constituents of the tropho- 
nucleus (see below), it is clear that their reactions agree very 
closely with the intra-nuclear chromatin. In preparations in 
which the stain is extracted from the intra-nuclear chromatin, 
leaving the karyosome sharp, it is also extracted from the 
chromatoid grains. When the intra-nuclear chromatin is 
coloured, the chromatoid grains are also coloured, and to 
about the same tint. On these grounds I infer that the 
chromatoid grains represent extra-nuclear chromatin or chro- 
midia, derived from the trophonucleus, possibly from the 
karyosome (see below). 
In ordinary preparations the cytoplasm does not contain 
any other enclosures than the chromatoid grains. In my 
standard preparations, however, examined in the wet blood, 
I find a body which is not to be made out in trypanosomes 
examined in Canada-balsam or cedar oil (figs. 1-8). Quite 
constantly a refringent granule is seen, sharply and dis- 
tinctly, in the post-nuclear region, sometimes close behind 
the kinetonucleus, sometimes nearer the pointed posterior 
termination of the body. It has the usual appearance of 
a refringent granule appearing as a black dot at the 
lower focus and as a clear spot at the higher focus. It is 
more refringent and much more distinet than the unstained 
kinetonucleus. .At first I thought it might be Prowazek’s 
“anchoring granule,” but I do not find anything anchored 
to it, and it disappears in the stained and mounted preparation. 
This is probably due to the fact that the granule itself does 
