768 E. A. MINCHIN. 
In extreme cases (PI. 21, fig. 38) the appearance of the fla- 
gellum recalls that of a wire that has been untwisted from the 
neck of a soda-water bottle. 
In films fixed with osmic acid vapour before being put into 
Flemming’s fluid, I find but little difference from those fixed 
with absolute alcohol after the osmic treatment, except that 
the trypanosomes are rather broader in proportion to their 
length (figs. 80, 81). ‘The nucleus stained with Giemsa’s 
stain is a large red patch, as large as, or even larger than, 
the whole clear space seen after direct fixation with Flemming’s 
and Hermann’s fluids. When stained with iron-hematoxylin, 
after Flemming’s fluid preceded by exposure to osmic acid 
vapour (fig. 39), the nucleus of the trypanosome does not 
show the clear space round it described above, but appears as 
a broad oval or nearly circular in outline. The body shows 
no periplast-line and the flagellum has the normal appearance. 
Previous exposure to osmic acid vapour would appear, there- 
fore, to obviate some of the defective results obtained by the 
direct action of Flemming’s fluid. 
(5) Sublimate mixtures.—Three different sublimate 
mixtures were used for fixation: (1) Sublimate and acetic 
acid, (2) Schandinn’s fluid, (8) Mann’s picro-corrosive mixture. 
All three were used directly on the wet film. The first two 
were used also after previous exposure of the wet film to 
osmic vapour. In all cases the fixing solution was allowed to 
act for about half an hour on the film. 
(a) Sublimate acetic.—This was used in the proportion 
of 95 parts (by volume) of corrosive sublimate solution, satu- 
rated in distilled water, and 5 parts of glacial acetic acid. A 
mixture was also tried of 99 parts corrosive sublimate solution 
to 1 part of glacial acetic, but was found to produce very 
inarked shrinkage in the trypanosomes (PI. 21, figs. 12, 13) 
and was not used again. 
The fixative was used either directly on the films (figs. 19- 
22, 82-84, 88-91), or after previous exposure to osmic vapour 
(figs. 14-18, 75), in both cases without drying before putting 
in the sublimate solution. ‘The fixed films were stained in 
