1910.] The Development of Trypanosomes in Tsetse Flies. 383 



Experiment 1014. 





Day 

 of experi- 

 ment. 





Results. 





Date. 



Procedure. 



Posi- 

 tive. 



Nega- 

 tive. 



Remarks. 



1909. 

 June 18—22 



„ 23—24 

 „ 25- 

 July 17 

 July 18 

 „ 19- 

 Aug. 3 



1—4 



5— G 

 7—29 



30 

 31—46 



Flies fed on infected 



goat 

 Flies starved. 

 Flies fed on healthy 



goat, 1079 

 Flies starved. 

 FUes fed on healthy 



goat, 1344 



+ 

 + 





200 flies used. 



July 26, injected in- 

 fected fly into a goat 

 and monkey, the 

 former of which be- 

 came infected. 



Aug. 4, 17 remaining 

 flies dissected ; all 

 negative. 



Remarks. — Two hundred wild flies were fed for five days on an infected goat. Twenty- 

 one days after their first feed they became infective, and remained so during the 

 experiment. On the 38th day one infected fly was found, which on injection into a 

 goat and a monkey gave rise to Trypanosoma vivax infection in the former animal. 

 Seventeen flies remained alive at the end of the experiment, and were killed and 

 dissected. None of them was found to harbour flagellates. 



Table VIII. — Number of FHes found infected with Trypanosomes in the 

 Experiments with Lake-shore Flies and Trypanosoma vivax. 



Experiment. 



No. of 

 flies used. 



Experiment, 

 positive or 

 negative. 



No. of 

 infected flies 

 found. 



Result 

 of injection of 

 infected flies. 



Remarks. 



997 



60 



+ 



2 







998 



45 



+ 



2 



+ 



14 flies remain- 













ing pooled. 



1014 



200 



+ 



1 



+ 





Of the above three positive experiments it is seen that five infected flies 

 were found. One of these — Experiment 1014 — when injected into a 

 susceptible animal gave rise to Trypanosoma vivax infection. In 

 Experiment 998, among the 14 remaining flies, two were found with 

 trypanosomes in their probosces. None of the 14 showed flagellates in the 

 gut. The body-contents of the 14 flies, in addition to the contents of the two 

 probosces, were pooled and injected into a goat, which 12 days afterwards 

 showed Trypanosoma vivax in its blood. 



