492 MITZMAIN. 



Guinea pigs C and A used in Table VII received their infec- 

 tions from subcutaneous inoculations of the peritoneal fluid of 

 guinea pig 128 which was a mate to guinea pig 127, receiving 

 the disease from an emulsion of infected house flies. Death 

 of 128 occurred on the fifty-second day after the injection. 

 Guinea pig C died forty days after inoculation. Numerous 

 trypanosomes were seen in a drop of its heart's blood. Guinea 

 pig A was also positive at death fifty-four days after injection. 

 Blood taken from the spleen was found swarming with trypa- 

 nosomes. 



After the experiments the horses were replaced in the fly- 

 screened stable where they were held for thirty days for ex- 

 amination. During this period no symptoms of surra developed, 

 after which blood was drawn from each, and inoculated into 

 guinea pigs. The horses were further tested as to susceptibility 

 to the disease by the inoculation of infected blood from a sick 

 guinea pig. Trypanosomes were recovered from horse 275 on 

 August 17, 1912, and from horse 279 on the same day. The 

 characteristic febrile changes occurred in both horses beginning 

 on the evening of August 17, 1912. 



MECHANICAL TRANSMISSION BY SUCCESSIVE INTERRUPTED FEEDINGS. 



In this series of experiments 3 guinea pigs were subjected to 

 interrupted bites of infected flies for from six to eight days. 

 Guinea pig 177 was bitten from June 20 to June 27 by 40 flies, 

 guinea pig 187 was bitten from June 28 to July 5 by 28 flies, and 

 guinea pig 129 received the bites of 206 flies from June 30 to 

 July 5. Laboratory-bred flies were not used in the first two 

 experiments as the breeding jars were not productive at this 

 time. In the third experiment laboratory-bred flies were used 

 daily during the course of the experiment. 



In the experiment with guinea pig 129 as the host, the flies 

 were applied in the six days during thirty-two hours, which 

 represents a fairly constant infestation by infected flies. The 

 precaution was taken in this instance, as in the other experi- 

 ments, to distribute the feeding area over various parts of the 

 body in order to abrade the skin as little as possible each day. 



The usual animal stock was employed as well as the method of 

 feeding individual flies from test tubes. A fresh collection of 

 flies was used daily. 



