N. H. SWELLENGREBEL 
237 
little altered. Fig. 7d may furnish the explanation. Here the darkly 
coloured plasma is also to be seen, but its outlines are not so sharp as in 
Fig. 7a. The remaining parts of the cell are not empty as they seemed 
to be in the foregoing figures, but filled with plasma of a pale-blue hue. 
In Fig. 7a, 7c this part of the cytoplasma has not been stained. I think 
it probable that this structure indicates a morphological differentiation 
in the cytoplasma. It corresponds with some observations made with 
dried, Giemsa-stained preparations, where a darkly staining plasmatic 
band between nucleus and blepharoplast may frequently be seen 
(Fig. 2d). 
These structures were equally distinct with Heidenhain’s stain, but 
only after wet fixation with alcohol. After Flemming’s fixation a 
median darkly staining band composed of irregular granules between 
nucleus and blepharoplast was to be seen (Fig. od). Perhaps this string 
of granules has something to do with the periplast line. I think they 
are to be identified with Minchin’s “ cbromatoid granules ” but they did 
not stain well with Ehrlich’s or Delafield’s hematoxylin, so I am not 
sure of it. 
Wh en comparing the influence of the different methods of fixation 
and staining on the cytoplasma we may conclude that the dry fixation 
Giemsa method is not inferior to the others. 
5. General cell form. To be able to express the value of the 
different methods of fixation in numbers, I measured a quantity of 
Trypanosomes fixed with different fluids, 10 cells for each method. 
Like Minchin I measured : 
(a) The part of the cell posterior to the posterior end of the 
blepharoplast (post-nuclear). 
( b ) The part between the anterior pole of the nucleus and the 
posterior end of the blepharoplast (intranuclear). 
(c) The part between the anterior pole of the nucleus and the end 
of the undulating membrane (prenuclear). 
(d) The greatest breadth. 
(e) The length of the whole cell (free flagellum excepted). 
Table II gives the results of these measurements. 
The results of these measurements correspond exactly with those 
of the morphological study and of the measurements of Table I. 
Flemming’s and Hermann’s stains produce general deformation, so does 
wet alcohol fixation, but this is not so marked. The best preparations 
are to be obtained with alcohol fixation of dried films or with fixation in 
corrosive-alcohol, osmic acid and Rath’s fluid. 
