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Notes on Certain Aspects of the Development of Trypanosoma 

 gambiense in Glossina palpalis. 

 By Muriel Bobertson. 



(Communicated by Sir J. It. Bradford, Sec. B.S. Beceived February 26, — 

 Bead March 28, 1912.) 



In the course of an attempt to obtain an insight into the details of the life- 

 cycle of Trypanosoma gambiense in Glossina palpalis, certain experiments were 

 undertaken involving the feeding of a relatively large number of flies under 

 closely observed conditions. Although primarily undertaken with a view to 

 the morphology and development of the parasite, they have a bearing on the 

 general relation between the trypanosomes and the Glossina that is of some 

 interest. 



The present account deals with the infections produced in the flies as a 

 whole ; the morphological results will be considered in detail elsewhere. I 

 must point out that the experiments in question are not concerned with 

 actual transmissions of T. gambiense from an infected to a clean host, but 

 with the number of flies in which the trypanosomes will develop. That flies 

 harbouring trypanosomes are infective from about the 26th day onwards has 

 been shown over and over again ; it was therefore considered to be a 

 wanton waste of life to allow every cage kept beyond the 30th day to 

 infect a clean animal. Late cages were usually fed on cock's blood after 

 the 24th day. A small proportion were actually tested and an infection 

 was invariably produced if the box contained flies showing trypanosomes. 



There is no evidence to show that a trypanosome-infection once established 

 in the fly is ever got rid of subsequently. T. gambiense may be held to be 

 established if the gut shows trypanosomes after the 5th day in flies which 

 have had at least one feed of clean blood subsequent to the infecting feed. 



This last statement bears on a point of some importance ; it has been 

 found during the course of these experiments that flies allowed to have one 

 infected feed and then starved absolutely, when dissected between the 6th 

 and the 12th day, show an extraordinary number of individuals in which 

 trypanosomes are to be found. Flies starved in this way rarely live beyond 

 the 12th or 13th day. These experiments will be referred to as starvation 

 experiments. 



Of 103 flies so treated and fed (for one infecting feed only) in groups on 

 different monkeys infected with T. gambiense, 22 showed trypanosomes 



