322 Col. Sir D. Bruce and others. Antelopeasa [Nov. 9, 
Table III.—Giving the Percentage of Flies which became Infected when Fed 
on Infected Antelope. Flies fed at first on the infected antelope and 
afterwards only on healthy monkeys. ' 
| 
; No. of | Percent- 
No. of Species of No. of | No. of |s potted ree 
experi- antelope flies flies _ flies vce Gar eeE Sa Remarks. 
ment. fed on. used. | dissected. ee flies. 
2346 | Bush-buck 2328 160 122 21 Mires The gut-contents of 6 
| infected flies injected 
| | into a rat gave it Sleep- 
| ing Sickness. 
| 2384 3 2328 100 91 10° Ala dO No injection of infected 
; flies. 
| 2414 a 2328 70 70 9 12°8 Five infected flies in- 
| jected into a rat gave 
| it Sleeping Sickness. 
2501 é, 2328 | 100 57 12 | 21:0 | No injection of infected 
| flies. 
2351 | Reed-buck 2857 100 84 9 10°7 - 3 
| 2507 7 2359 200 80 2 2°5 Ke Oe 
| 2477 | Bush-buck 2371 , 60 | AT 4 8°5 ie n Fs 
| 2478 | Water-buck 2378 60 | — — — Negative experiment. 
| Flies not dissected. 
2559 ” 2378 | 60 pes aun Ae ” ” ” 
2454 | Reed-buck 2427 110 92. | 18 14-2 One infected fly injected 
into a rat gave it Sleep- 
| ing Sickness. 
2485 | Bush-buck 2428 , 50 26 | 3 11 °5 No injection of infected 
flies. 
2460 | Reed-buck 2429 50 BS lian 13 ‘1 i, y 5 
2543 a 2429 100 — | = — Negative experiment. 
| Flies not dissected. 
2544 > 2431 90 53 5 16 ‘6 No injection of infected 
| flies. 
2592 sy 2431 | 100 Sel el alas 2 " 2 
2476 4 24.45 50 _— _ — Negative experiment. 
Flies not dissected. 
Remarks.—Of these 16 experiments, 12 were positive and 4 negative. In the positive 
experiments, 838 flies were dissected. Of these, 94 showed heavy intestinal infection with 
developmental forms of Trypanosoma gambiense, viz., 11°2 per cent. Of these infected flies, 
43 were males and 51 females. If to these 838 flies be added all the Glossina palpalis of the. 
negative experiments, we get a total of 1108 flies, and a percentage of 8°5 infected. In only 3 of 
the positive experiments was an injection made into susceptible animals of the citrated gut-contents 
of the infected flies. All three gave positive results. 
that a higher percentage of negative results were obtained where fowls were 
introduced into the experiments. In some of the experiments the flies were 
dissected as they died throughout the whole experiment, and in others the 
flies were dissected only when the experiment became positive. If the 
experiment was a negative one the flies were not dissected. In order 
to avoid over estimations of the percentage of infected flies, no fly was called 
infected unless its gut was swarming with trypanosomes, and all the flies 
dissected during the earlier days of the experiments have been included. 
