510 



MITZMAIN. 



In this experiment the eggs produced by several hundreds of 

 wild flies were placed, April 27, 1912, in a jar containing a 

 medium of horse manure with fresh blood from a surra horse. 

 The blood was lightly infected on this day. On May 2, the larvse 

 were changed to a clean jar with fresh, boiled manure, cooled 

 and sprinkled generously with heavily infected blood of a monkey 

 recently dead from surra. On May 4, pupse had formed, emer- 

 gence taking place five days later when 11 flies appeared. Forty- 

 eight flies were fed daily as they emerged from May 9 to 13, 

 inclusive, on monkey 2M. On May 14, 12 flies remained, and 

 of these 7 fed on the monkey. After feeding, the flies were 

 emulsified and inoculated into guinea pigs 93 and 94, which after 

 the usual tests did not react. 



Within two to three days after the blood was added to the 

 fly-breeding medium, the presence of the blood diet could be de- 

 tected by the terra-cotta color of the alimentary tract of the 

 larvse. The surra-blood-fed larvse were not injected to demon- 

 strate the presence of the specific organism; however, it is 

 thought that the disease could be reproduced by animal inocu- 

 lation with fresh material. Trypanosomes were found on micro- 

 scopical examination in larvse four hours after the introduction 

 of the infected blood. These had been passed through four 

 changes of salt solution prior to macerating for examination. 



The data embodied in Table XVII represent a summary of 

 all of the foregoing experiments in the attempts to convey the 

 infection of surra by the agency of Stomoxys calcitrans. 



Tablb XVII. — Summarized data of feeding experiments with Stomoxys. 



Time after feeding: 

 on Infected ani- 

 mala that the flies 

 were applied. 



Immediate to 48 



hours. 

 6 minutes to 63 



hours. 

 10 minutes to 8 



days. 

 21 hours to 81 days. 

 20 seconds to 2 



minutes. 



1 to 3 minutes 



25 to 30 seconds... 

 6 seconda to 1 min- 



ut«. 



Num- 

 ber of 



pen 



ments. 



Total 

 number 

 of flies 



used. 



26, 666 

 225 

 565 



1 



173 



139 

 63 



274 



Number and 

 kind of ani- 

 mals exposed 

 to infected 

 flies. 



3 horses 



3 guinea pigs. 



Nature of experi- 

 ment, or method 

 of applying flies. 



Direct completed ! Negrative. 



feeding. 

 do Do. 



6 monkeys and do 



19 guinea pigs, i 



31 guinea pigs ..j do 



11 guinea pigs ._; Direct interrupted 



; feeding. 

 14 monkeys ; do 



2 horses ! do 



3 guinea pigs --- 1 Successive inter- 



i rupted feeding. 



Do. 



Do. 

 Do. 



Do. 

 Do. 

 1 positive, guinea 

 pig received 

 206 bites dur- 

 ing 6 days. 



