TRYPANOSOMES IN TSETSE-FLIES AND OTHER DIPTERA. 169 
classic Romanowsky stain, using either Leishman’s method, 
Laveran’s Bleu-Borrel method, or Giemsa’s stain. Latterly 
I used Giemsa’s stain entirely, differentiating with tannin- 
orange solution (Unna’s, obtained from Griibler). As a rule 
the smears were “refreshed” with fresh blood-serum, after 
the procedure recommended by Leishman. I kept my smears 
uncovered. Those that have been much used for study are 
now, I find, deteriorating, but those that have not been much 
looked at seem to be quite unaltered. Frequent baths of 
cedarwood oil and xylol alternately effect the stain after a 
time. Some smears, owing to pressure of time, were left unfixed, 
and were fixed after my return ; none of these were very good. 
Parasites of Glossina palpalis.—lI examined the con- 
tents of the digestive tract and other organs in freshly- 
caught hungry flies with the object of making myself 
acquainted with the native parasites, if any, of the fly, in 
order to avoid confusing with them the stages of trypano- 
somes. Except for bacteria, however, the fly was very free 
from internal parasites. No gregarines or other sporozoa 
were found ; it would, indeed, be improbable that a tsetse-fly, 
which apparently feeds exclusively on the blood of verte- 
brates, should acquire an infection of such parasites, which, 
as a general rule, are taken up with food in an encysted form 
by their hosts. 
The commonest object in the gut was a large bacillus 
(figs. 111-123), apparently always present, sometimes in 
enormous numbers, especially in the stomach. When plenti- 
ful they occurred in masses or bundles; in such cases the 
flies always appeared sickly, emaciated, and anemic, and 
usually had the digestive tract empty of blood, even when 
they had been put on to an animal; whether through the 
fly refusing to feed, or through rapid absorption of the blood 
by the bacteria, was doubtful. These bacteria show, 
apparently, only Brownian movement.! 
1 Stullmann (41, pp. 38, 39), has seen these or similar bodies in G. fusca. 
He believes them to be protozoa and not bacteria, and considers that they 
are not parasites because they are found to be invariably present. I cannot 
agree with him in either of these conclusions. 
