43 



[nfectivity of Glossina morsitans in Nyasaland during 1912 and 



1913. 



Ey 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, B.A.M.C. ; and Lady 

 Bruce, K.B.C. (Scientific Commission of the Boyal Society, Nyasaland, 

 1912-14.) 



(Received April 7, — Read June 18, 1914.) 

 Introduction. 



The object of this paper is to attempt to set up a rough standard of the 

 proportion of infected to non-infected tsetse flies in an ordinary " fly-area " 

 where wild game abounds. It is thought that a standard of this kind may 

 prove useful in the future. 



The flies were collected in the low country lying near the Commission's 

 ■camp at Kasu, in what is known as the " Proclaimed " or Sleeping-Sickness 

 Area of Nyasaland. This bit of country swarms with Glossina morsitans 

 and wild game, the latter highly infected and well protected. 



In 1912 a total of 1975 flies were dissected between the months of 

 January and November. Of these 129 were found to be infected with 

 .trypanosomes — 6*53 per cent. Males, 86 per cent". ; females, 14 per cent. 



In 1913, 1060 flies were dissected, of which 91 were infected — 

 ■8 - 58 per cent. 



The following Tables give the details : — 



Table I.— 1912. 



No. of fly. 



Proboscis. 



ProTentri- 

 culus. 



Crop. 



Intestine. 



Salivary 

 glands. 



Part of fly injected. 



Animal 

 injected. 



Result. 



1 



+ + 



+ + 



+ + 



+ + 











2 









+ 





Intestine 



Dog 





3 







+ 



+ + 







33 





4 



z 







+ 





>3 



Goat 





5 









+ + 





V 



Dog 





6 









+ + 





)j 



Goat 





7 





+ + 





+ + 











8 



+ + 







+ + 





Proboscis 



Dog 





9 



+ + 











Goat 





10 



+ 



+ 





+ + 







13 





11 









+ 











12 









+ 











13 









+ + 





Intestine 



Dog 





14 



+ + 







+ + 









15 









+ + 











16 









+ + 











17 



+ 

















18 









+ + 











19 



+ 

















