354 Col. Sir D. Bruce and others. Yabamde  [Dee. 20, 
not being fed. The daily temperature of the laboratory during the days this 
method was tried was very constant, being 70°2 F. (21°:2 C.) in the morning 
at 8, and 80°2 F. (26°'8 C.) in the afternoon at 4. The flies were placed on 
oxen and monkeys for 20 minutes once daily, to give them ample opportunity 
to feed. 
This method was not successful, the flies—TZabanus secedens (Walk.)— 
all dying within four days of being caged, the majority within 48 hours. 
When placed’ on an ox, within 12 hours of capture, a few flies fed greedily. 
After 24 hours in the cages no fly was observed to bite. Monkeys were 
never bitten by the flies, though they would feed on man as readily as 
on the ox when freshly caught. If shaded from direct sunlight, the flies 
refused to feed. 
It was decided to build a fly-proof kraal in the natural haunts of the fly, 
in the hope that the Tabanidze would live longer and feed more readily. 
The Kasala stream at the foot of Mpumu hill was chosen as the site of the 
kraal. The kraal was divided into two compartments, which were made 
fly-proof from each other and from the outside. In one compartment no 
flies of any species had access. Into the other compartment the species of 
Tabanus under experiment were liberated—50 flies per day, on an average. 
In the kraal four calves were kept; three normal and one calf infected with 
Trypanosoma pecorum. The infected calf and two of the normal calves were 
taken from the fly-free compartment into the compartment containing the 
Tabanide for three hours daily. The hours chosen were 11 A.M. to 1 PM., 
and 3 P.M. to 4 P.M., when the sun was hot and shining on the kraa]l. Every 
opportunity was thus given to the flies to feed on both the infected and the 
healthy calves. The other normal calf was utilised as a control, being kept 
continuously in the fly-free compartment and so protected absolutely from 
the bites of blood-sucking flies. 
No effort was made to rid any of the calves of ticks, body lice, etce., 
therefore, if the normal calves which daily entered the fly-compartment , 
with the infected calf contracted Zrypanosoma pecorum infection whilst the 
control calf remained healthy, then the Tabanus under experiment was in 
all probability the transmitting agent. If the control calf also contracted 
the disease, then some agency other than Tabanide, such as ticks, etc., would 
probably be responsible. Lastly, if all the normal calves escaped infection, 
then presumably the Tabanus under experiment did not transmit the disease. 
The Tabanide did not appear to live more than three or four days, in spite 
of the presence of running water, shrubs and foliage in the fly-compartment. 
The majority died within the first 48 hours. A few fed greedily on the 
calves for 12 to 18 hours after capture. 
