2 o8 
V. TWELVE TO FIFTEEN HOURS INTERVAL 
To infect a susceptible animal with Trypanosoma gambiense by 
the bites of tsetse flies fed at least 12 to 15 hours previously on an infected 
animal or man. 
Leopoldville. 
Experiment 48.—Guinea-pig. From December 12 , 1903, to April 6, 1904, 1,706 
flies were fed. The blood was regularly examined until April 12, 1904, when the 
animal died, trypanosomes were never seen in its blood nor in any of the body- 
Hinds or organ-juices examined at the autopsy, done immediately after death. 
1 .xPEKiMENi 6i. Rat. l-roni December 23, 1903, to May 20, 1904,4846165 
were fed on this animal. Its blood was regularly examined' until July 3, .904, 
v en 1 was accidentally killed. Trypanosomes were not seen. 
I.xi iI'.kimi m (>2. Rat. I' rorn December 23, 1903, to February 25, 1904,261 
les led on this animal. No trypanosomes were ever seen in its blood. It died 
on March 1, 1904, of a lung disease. 
Experiment 71.— Rat. From December 18, 1903, until May i 5 , 1904, 4 >7 
weit. ec cm this animal. Its blood was regularly examined for trypanosomes 
without result until July 7 , ,904. when it was accidentally killed. 
In the four preceding experiments it was attempted to transm 
the trypanosomes from animal to animal; in tiie three following 
was attempted to transmit them from man to animal. 
this an imai ^ V * rom January 16 to April 9, 1904, 999 flies were fed f 
result until Ini * ’ "tf re 6 uIarl 3 ' examined for trypanosomes with negati’ 
result until July ,, ,904, when it Was accidenta] , y 
fed on'^his'ammal '' l 7 s' blood' 1 ” 8 ' Kr0 !" ApriI ' 3 to May 3 °. * 9 ° 4 . 39 ° fiies wel 
at intervals until October 8 wh^ eXa "" ned re S uIarl - v until June 1, and afterwarc 
aniinarreacdon 1 o^a , Congo ,, cattle' / trypanosonie? X ^ er ' nientR “* 
Kasongo. 
'905, 542 fl ies, N preyfousk^fecT on ^ S P - ? >- From January 24 to April 5 
Its blood was examined f a ■•’leeping sickness patient, fed upon this animal 
were never .seen fieqUent, F ,,nt " ”as stolen on May 4 : trypanosomes 
April 20, 1905, 46 l 1 ies M °n" k :?' -i erc t °^ ithecus schmidti). From February 25 to 
monkey. () n April 2c it °'' s - v on an infected animal, were fed on this 
therefore killed. Nntrvn^!^ ad, - v in j ure d by its cage companions, and was 
autopsy, nor were there any’X'n * durin S Iife < maIaria presenti, or at the 
y s, 8 ns nf trypanosomiasis. 
