Development of Trypanosoma gambiense in Glossina palpalis. 405 



Fig. 19. — Single specimen after treatment with 2^-per-cent. commercial formalin, showing 

 both the parietal and the more internal portions of the protoplasmic network. 

 The granules are shown only in the upper parietal portion of the network. 



Fig. 20.— -One extremity of an individual after treatment for 14 days with acidulated 

 pepsin-glycerin. Only the granules o'f the surface network are represented ; 

 these stand out very clearly, but the protoplasmic network itself has been for 

 the most part digested. 



Fig. 21.— One extremity of an individual after treatment for 14 days with a concentrated 

 solution of Na s C0 3 . Only the surface network is represented. The proto- 

 plasmic network remains clear and distinct, but most of the granules have 

 been dissolved. 



The Development of Trypanosoma gambiense in Glossina 



palpalis. 



By Colonel Sir David Bruce, C.B., F.E.S., Army Medical Service ; Captain 

 A. E. Hamerton, D.S.O., and H. K. Bateman, Koyal Army Medical 

 Corps ; and Captain F. P. Mackie, Indian Medical Service. (Sleeping 

 Sickness Commission of the Royal Society, 1908.) 



(Received July 5, 1909.) 

 [Plates 10 and 11.] 



The following experiment is so complete in itself that no apology is offered 

 for publishing it by itself. In 1903 the Sleeping Sickness Commission of the 

 Royal Society came to the conclusion that the carrying of infection from 

 a sleeping sickness patient to a healthy person by the Glossina palpalis was 

 a mechanical act, and required no previous development of the parasite 

 within the fly. The Commission also held that the power of transferring 

 the disease was lost to the fly 48 hours after it had fed on an infected person. 



Koch and Stuhlmann, in German East Africa, described developing forms 

 in Glossina, but did not succeed in infecting healthy animals by the injection 

 of these forms. 



Kleine, in German East Africa, at the end of 1908, succeeded first in 

 showing that Glossina palpalis could convey Trypanosoma, brucei some 50 days 

 after the fly had fed on an infected animal. 



It seems, at first, strange that this fact should have escaped notice for 

 15 years, and can only be accounted for by assuming that it is an event of 

 the rarest for a fly to be found which fulfils the unknown conditions 

 necessary for the development of the trypanosomes in its interior. If we 

 assume that it is only one fly in a hundred or in a thousand in which this 



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