210 
Experiment 218.—Monkey [Cercofithecus sckmidti). From April 3 to April 14, 
I 9 ° 5 » 7 1 previously fed on a sleeping sickness patient, were fed on this 
monkey. The blood was examined at intervals until June 5; trypanosomes were 
never seen. The animal was moribund on June 5; it was therefore killed and an 
autopsy was made immediately. No trypanosomes or signs of trypanosomiasis 
were observed. 
IX. FOUR DAYS INTERVAL 
lo infect a susceptible animal with Trypanosoma gambiense 
by the bites of tsetse flies fed at least four days previously on a sleeping 
sickness patient. 
Leopoldville. 
Experiment 74.— Guinea-pig. From December 30, 1903, to May 29, 1904,42 
les were e on t is guinea-pig. Its blood was examined regularly until Octobei 
904. w en 1 died of coccidiosis. No trypanosomes were ever seen. 
ExpERrMi.Ni 122. Monkey' [Cercofithecus sckmidti). From April 24 to June 1 
1904, ^o 9 flies were fed on this monkey. Its blood was examined regularly unti 
j 6 W en 11 was acc identally killed. Its temperature had alwavs been normal 
and at the autopsy, as during life, trypanosomes were not seen. 
It was thought that perhaps the trypanosomes underwent a lengthy 
developmental process in the tsetse fly, and that therefore the scanty 
success of the preceeding experiments might have been due to the 
shortness of the interval between the infecting and transmitting feeds. 
n t le two following sets of experiments this period was consequently 
greatly increased. 
X. TEN DAYS INTERVAL 
, ln J ec ^ a susceptible animal with Trypanosoma dimorphor 
animal ^ tes 11 ^ ^ cas * ^ en days previously on an infect a 
Kasongo. 
fed ; in many instant ^ ,n *' lca 'P*S- 1 ‘rom March 23 to April 25, 1905. 210 fli? 5 
transmitting feed.' The hi ' '? * ,nterven f d between the first infecting feed and the 
sonies were ever seen C k'.’° - Wa ® examined regularly until August 4 ; no trypano- 
i 9 ° 5 , when the animal i- all,l ' ,atlons were then discontinued until September 18, 
autopsy. ammal d ‘ efl of tuberculosis. No trypanosomes were seen at the 
2905. 206 flies were / fed^° n * <eV ^ er f°l >tt ^ ecus sckmidti). F'rom April 2 to April 27. 
first infecting feed nnri tv, 1 " nianv j nst ances 25 to 30 days intervened between the 
U P to July 29 ; no try panosomeT Sm ,ttln ^ feed - The blood was examined regularly 
September 29, k,,,-’ n f c r. ‘ s ' vere ever seen (malaria present). The animal died 
were seen at the autnn«« 10eR ’ no ,r >’P ano somes or signs of trvpanosomiasi? 
autopsy done immediately after death. 
