234 
Trypanosoma lewisi 
the contrary, after dry fixation, it gives figures so sharp as may rarely 
be obtained with iron-hematoxylin. Moreover the achromatin is better 
differentiated and the method being a progressive one is more reliable 
than the degressive method of Heidenhain. As for the fixation after 
drying I never observed any sign of shinkage, of destruction, or even of 
the slightest dislocation of the nuclear structure. The figures observed 
in preparations made after this method are perfectly similar to those 
produced by the best methods of wet fixation. 
To be able to judge of the influence of the fixing fluids used on the 
shape of the nucleus I tried to obtain a numerical expression for it. 
Nuclei of Trypanosomes fixed by the different methods and stained by 
Giemsa (this stain marking very distinctly the outlines of the nucleus) 
were drawn with the camera lucida. On the same piece of paper used 
to draw the Trypanosomes a scale of 10 p was drawn (using an object- 
micrometer) so that the nuclei might be measured after they had been 
subjected to different methods of fixation. The following table gives 
the results of those measurements. 
This table confirms the results of the study of nuclear structure. 
Dry fixation, Corrosive alcohol and Osmic acid give the best results. 
Absolute alcohol and the Picro-corrosive mixtures are a little inferior, 
Hermann’s and Flemming’s liquids are not favourable. 
TABLE I. 
Showing the average size of the nucleus in Tr. lewisi after using different 
methods of fixation. 
Films stained by 
Giemsa. 
Longitudinal 
Transverse 
Fixative 
diameter 
diameter 
Corrosive-alcohol 
21 
0-9 
Dry fixation 
2-3 
0-9 
2 °/ 0 osmic acid 
2 0 
0-8 
Absolute alcohol 
1-9 
0-7 
Bath’s liquid 
1-8 
0-7 
Babl’s liquid 
1-8 
0-7 
Hermann’s liquid 
1-8 
0-4 
Flemming’s liquid 
1-8 
0-5 
2. Blepharoplast. (Minchin’s kinetonucleus.) The structure of 
the blepharoplast after fixation and staining by different methods may 
vary considerably in appearance depending upon the total or partial 
staining of its component parts. 
After fixation with corrosive alcohol and staining with iron- 
hematoxylin, the blepharoplast presents itself as a rodlet (Fig. 3) 
