213 



The Trypanosome causing Disease in Man in Nyasaland. The 

 Naturally Infected Dog Strain. Part III. — Development in 

 Glossina morsitans. 



By Surgeon-General Sir David Bruce, C.B., F.R.S., A.M.S. ; Major A. E. 

 Hamerton, D.S.O., and Captain D. P. Watson, R.A.M.C. ; and 

 Lady Bkuce, R.R.C. (Scientific Commission of the Royal Society, 

 Nyasaland, 1912-14.) 



(Received May 5, — Read June 25, 1914.) 

 Introduction. 



In previous papers* the morphology and action on animals of this strain 

 of trypanosome were described. In this a short account of its development 

 in Glossina morsitans is given, in order to compare it with the development 

 of the Human strain of the trypanosome causing disease in man in 

 Nyasaland.t 



It is to be regretted that more material is not available, but, scanty as it 

 is, there is enough to show that this strain develops in the alimentary tract 

 and salivary glands of Q. morsitans in the same way as the TrypoMOSoma 

 brucei and garnbiense group. The Commission aimed at having five positive 

 experiments in every series of transmission experiments, but in this case 

 failed. The failure was principally due to the difficulty of procuring 

 laboratory-bred flies, and also to the fact that this strain of trypanosome 

 does not readily develop in G. morsitans. 



The Development of thk Naturally Infected Dog Strain in 



g. morsitans. 



Eleven experiments were made with laboratory-bred flies. Two were 

 positive and nine negative. 



Three hundred and seventy-six flies were used and fourteen were found 

 infected — 3'7 per cent. This small percentage is partly due to the fact that 

 , in some of the experiments few or none of the flies were dissected. There 

 is the same discrepancy to.be noted here as in T. brucei, Zululand, 1913. In 

 some of the experiments not a single infected fly was found, whereas in 

 Experiment 2018a there were seven in a cageful of 36. 



* 'Eoy. Soc. Proe., : B, vol. 88, pp. Ill and 130 (1914) 

 + Ibid.. B, vol. 87, p. 515. 



