1912.] 



Reservoir for Trypanosoma gambiense. 



305 



Previous to Experiment 653 a period of nine months had elapsed without a 

 positive result being obtained. Considerable caution is therefore necessary in 

 pronouncing these antelope negative. It may be noted here that, as in the 

 case of Monkey 199 inoculated from Eeedbuck 2359, the strain of trypano- 

 somes in Monkey 653 appears peculiarly adapted to development in 

 G. palpalis. Sufficient time has, however, not yet elapsed to definitely 

 establish this point. 



Waterbuck 2378. 



Original infection, April, 1910. Latest evidence of infectivity afforded by 

 positive G. palpalis in August, 1910. 



Fly Experiments. 



Expt. 

 No. 



Period for which flies 

 fed upon 2378. 



Number of flies. 



Length 



° f . 

 experi- 



Eesult 



of 

 feeding 



clean 

 monkey. 



Remarks. 



1st 

 day. 



30th 

 day. 



Dissected 

 during 



ment. 



Con- 

 taining 

 flagel- 

 lates. 



344 



Aug. 30- Sept. 2, 1911 



65 



45 



64 







- 







These flies were nourished on a cock during the earlier days of the 

 experiment. 



Injection Experiments. 



Date. 



Expt. No. 



Quantity of blood injected. 



Eesult. 



Animal used for 

 injection. 



Pure. 



Citrated. 



2.5.11 



35 





4 





Monkey. 



22.7.11 



216 



3 







23.1.12 



627 











10.2.12 



650 



8 







There is therefore no evidence to show that the waterbuck has been 

 infective to T. gambiense during the last 18 months. The last positive 

 experiment occurred four months only after the original infection. On 

 August 10, 11, 12, 1911, this waterbuck was fed upon by positive flies. 

 Experiment Box 22, which was subsequently shown to contain an infected fly, 

 and which had proved infective to a number of animals. Sufficient experi- 

 ments have not been carried out to justify a decision as to the immunity 



