1910.] The Development of Trypanosomes in Tsetse Flies. 385 



Experiment 1698. 



Date. 



JUay 

 of experi- 

 ment. 



1 



procedure. 



Result. 

 Positive. 1 Negative. 



•D 1 



Kemarks. 



1909. 













Sept. 21—24 



1—3 



Flies fed on infected 







68 flies used. 





ox 







Calf 1893 died 



1 „ 25—26 



4-5 



Flies starved. 







29.11.09. 



1 27- 



6—45 



Flies fed on healthy 



+ 





Nov. 12, 53 flies re- 



1 Nov. 5 





ox, 425 







maining alive dis- 



Not. 6—9 



46-49 



Flies fed on healthy 







sected ; probosces of 







calf, 1893 







5 swarming with 



„ 10-11 



50—51 



Flies starved. 







flagellates. 



Remarks. — Sixty-eight laboratory-bred flies were fed for four days on an ox whose 

 blood contained Trypanosoma vivax. About the 35th day the flies became infective. 

 On the 52nd day the 53 flies which remained alive were killed and dissected. The 

 probosces of five, three males and two females, were found to be swarming with 

 flagellates. Tliese were not injected into animals. 



Experiment 1700. 



Date. 



Day 

 of experi- 

 ment. 



Procedure. 



Result. 



Remarks. 



Positive. 



Negative. 



1909. 

 Sept. 21—24 



„ 25—26 

 27- 

 Oct. 28 



1—3 



4—5 

 6—37 



Flies fed on infected 

 ox 



Flies starved. 

 Flies fed on healthy 

 calf, 290 



-1- 





60 flies used. 



Oct. 30, 38 remaining 

 flies dissected ; 22 

 found infected. 



Remarks. — Sixty laboratory-bred flies were fed for four days on an ox whose blood 

 contained Trypanosoma vivax. About the 30tli day these flies became infective. On the 

 39th day the 38 remaining flies were killed and dissected. There were 19 males and 

 19 females ; 22 showed infection of the proboscis with crithidia-like flagellates. Only 

 one fly showed flagellates in the gut. Of the 22 flies which had trypanosomes in the 

 proboscis, 9 were males and 13 were females ; 10 of the infected probosces were gi'ound 

 up in salt solution and injected into an ox ; 12 days afterwards trypanosomes appeared 

 in the blood of this ox. 



Experiment 1870. 



Remarks.— Fiity laboratory-bred flies were fed on a calf whose blood contained 

 Trypanosoma vivax ; 10 and 12 days afterwards all the flies were killed and dissected. 

 No flagellates were found in any part of the flies. 



