BY C. J. POUND, F.R.M.S. 37 
gellum threading its way between the corpuscles, drawing 
the body of the organism after it, thus, as Crookshank states, 
the flagellum acts as a tractellum and not as a pulsellum. 
This feature of the movement cf the flagellum in front drawing 
the body of the organism behind is almost a distinct peculiarity 
of such low types of animal life as the Protozoa. 
All the trvpanosoma are decidedly polymorphic, but as a 
rule they have slightly taperig bodies which terminate at 
one end with a stiff acutely pomted process, while the opposite 
end is provided sith a long flagellum, which 1s a really « con- 
tinuation of a delicate fin-like membrane attached to nearly 
two-thirds of the back of the organism. When carefully 
examined under a critical high power objective, the body 
substance is seen in parts to be distinctly granular and possess- 
ed of two or more highly refractive spherules ; the one in the 
centre of the body being the nucleus, while at the posterior 
end there are usually two, one of which is the centrosome, 
and the other the pulsating vacuole. 
The average size of the body of a trypanosoma is about 
20 to 30 micro-millimetres long, and from 0.8 to 1 micro- 
millimetres broad ; while the flagellum is about as long as the 
body, so that the total length of the organisms would be about 
50 micro-millimetres, in fact many of them are in length 
from six to eight times the diameter of a red blood corpuscle, 
or roughly speaking the 5), of an inch. 
Nothwithstanding that trypanosoma may be detected 
in the blood in the living condition it is a very distinct advan- 
tage to be able to examine them after they have been fixed 
and stained and permanently mounted. 
For this purpose | have been extremely successful 
in staiming them with methylene blue, gentian violet, and 
Bismarck brown, in either of which watery solutions the 
coverglass smears after fixing with absolute alcohol should 
be left for at least from 12 to 24 hours ; they are then washed 
im water and mounted in Xylol Balsam. One of the best and 
most permanent stains I find is carbol fuchsin: a little of 
this stain is placed in a watch glass, and the green metallic 
looking scum removed by the addition of two or three drops 
of alcohol. The coverglass smear is then floated, prepared 
