1910.] The Development oj Trypanosomes in Tsetse Flies. 381 



Experiment 1642. 



Date. 



Day 

 of experi- 

 ment. 



Procedure. 



Ees 



ult. 



Remarks. 



Positive. 



Negative. 



1909. 

 Sept. 8—11 



1—3 



Flies fed on infected 







50 flies used. 



„ 12-13 

 „ 14—28 



„ 29 

 „ 30— 

 Oct. 11 

 Oct. 12 



4—5 

 6-20 



21 

 22—33 



34 



oxen 

 Flies starved. 

 Flies fed on healthy 



ox, 870 

 Flies starved. 

 Flies fed on liealthy 



monkey, 1741 

 Flies starved. 



+ 





Oct. 13, 35 remain- 

 ing flies dissected; 

 all negative. 



Remarks. — Fifty laboratory-bred flies were fed on two infected oxen for four days, and 

 then on a healthy ox. Fourteen days after their first infected feed this ox took the 

 disease. 



These experiments with Trypanosoma dimorphon are not very satisfactory. 

 Experunent 574 appears to be fairly free from fallacy, and from it, it would 

 seem probable that Trypanosoma dimorphon can develop in Glossina palpalis 

 and infect a healthy animal after a period of 21 days. Ox 870, in Experiment 

 1642, became infected at a time when several of the cattle at Mpumu became 

 naturally infected with this trypanosome disease, so that this experiment is 

 not free from doubt. It is evident that more work must be done before 

 anything definite can be said regarding this species. 



E. The Development of Trypanosoma vivax in Lake-shore Glossina palpalis. 



Table VII. — Development of Trypaimsoma vivax in Lake-shore Glossina 



palpalis. 



Experiment. 



No. of flies. 



No. of 

 days fed on. 



No. of days before 

 flies became infective. 



No. of days flies 

 remained infective. 



997 



60 



4 



11 



48 



998 



45 



4 



11 



44 



1014 



200 



4 



21 



60? 



As Tryjmnosoma vivax does not affect monkeys, naturally cattle or goats 

 were used in these experiments. The three experiments with Lake-shore flies 

 were all successful ; two became infected in 11 days, and one in 21 days. 



Here follow the experiments in detail : — 



