8g o 



25 



34 o 



32 



^'^"^^^l LIFE-CYCLE 3O9 



Monkey 113. 



Percentage 



Date Condition of blood examined laboram.-y bred Number of beconi'ing 



^""= flies flies fed infected 



Aug. 20-22 No trypanosomes seen in blood No flies fed — — 



■• ""^ Few _ joi o 



24 Numerous trypanosomes in blood + 43 n-i 



^5 ^ ,, „ , + 2^ j.y 



26 Verjr numerous trypanosomes in 



blood . . . . . . _ 



27 Very few trypanosomes in blood No flies fed 



28 / No trypanosomes seen in blood Flies fed 



29 \ both days 



30 Few trj-panosomes in blood — 



31 ,. ,, ,, ,, + 107 i-S 

 Sept. 1-3 Not examined 



4 ^"ery few trypanosomes in blood — 



5 ,. ,, ,, ,, ,, No flies fed 



6 Moderate number of trypano- 



somes, dimorphism of broad 



and narrow forms very marked — 



7 Moderate number of trypano- 



somes . . . . . . No flies fed 



8 Trypanosomes very numerous 



indeed . . . . . . + 



9 Fair number of trypanosomes 



but much fewer than on 8th No flies fed 



10 Not examined .. .. No flies fed 



11 Few trypanosomes 



12 Trypanosomes ve y numerous 



indeed . . . . . . -1- 



13 Trypanosomes very numerous 



indeed .. .. .. No flies fed 70 1-4 



14 Trypanosomes very numerous 



indeed . . . . . . ,, — — 



15 Blood swarming with trypano- 



somes ...... + 20 10 



infected with T. gambiense by laboratory bred flies. The bush- 

 buck had harboured the trypanosome for about fifteen months. 

 This monkey shewed infective and non-infective periods in 

 exactly the same way as other infections, but the infective 

 periods gave a remarkably large percentage of flies harbouring 

 trypanosomes. Out of 150 G. palpalis that were fed on this 

 monkey, 16 became infected, a percentage of io-6 per cent., 

 which is remarkably high, for Bruce, Hamerton, Bateman 

 and Mackie found that the normal proportion of infected flies 



49 



95 



70 1-4 



