345 
Hapervments to Ascertain if Trypanosoma gambiense during its 
Development within Glossina palpalis 1s Infective. 
By Colonel Sir Davip Bruck, C.B., F.R.S., A.M.S.; Captains A. E. HAMERTON, 
D.S.0., and H. R. Bateman, R.A.M.C.; and Captain F. P. MaAckig, 
I.M.S. (Sleeping Sickness Commission of the Royal Society, Uganda, 
1908-10). 
(Received November 25, 1910,—Read February 2, 1911.) 
It will be remembered that the injection of chopped-up tsetse flies 
(Glossina morsitans) a short time after feeding on an infected animal, did not 
give rise to nagana. As this was thought to be an interesting fact, and 
difficult of explanation, experiments were carried out on the same lines with 
Trypanosoma gambiense and G'lossina palpalis. 
If tsetse flies (Glossina palpalis) are fed upon an animal whose blood 
contains Z'rypanosoma gambiense, the trypanosomes canbe found living within 
the intestines of some of the flies for several days after they were ingested. 
In a small percentage (0°5 to 2:0 per cent.) of flies so infected, active 
trypanosomes may be found swarming in their intestines on any day 
between the seventh and the fiftieth day, or even longer, after they have 
been fed upon an infected animal. 
A series of experiments were undertaken, to ascertain if Trypanosoma 
gambiense retained its power of causing Sleeping Sickness when inoculated, 
subcutaneously, into monkeys, throughout its period of multiplication within 
the fly, especially during the interval of some 20 days in which the bites of 
infected flies are harmless. In some of these experiments Lake-shore flies 
were used; in others, laboratory-bred flies. 
The flies were fed upon a monkey whose blood contained many trypano- 
somes. After a pre-determined time had elapsed, the wings and legs of the 
infected flies were cut off, and the bodies were either chopped up and 
brayed in a mortar with saline solution (0°8 per cent.), or the alimentary 
canal alone was removed. In many instances the gut was proved by 
microscopical examination to be heavily infected with trypanosomes before 
it was inoculated into a monkey. In flies thus found to be infected, the 
salivary glands also were carefully removed and washed thoroughly in 
several changes of normal saline solution. They were then broken up and 
injected, by means of a sterile syringe, into the subcutaneous tissue of the 
groin of a monkey. 
