226 The Philippine Journal of Science xm 



the day following, horse 50 showed numerous trypanosomes in 

 its blood and high temperature. Blood from this horse was 

 inoculated into a mule, 2 monkeys, and 2 guinea pigs. The mule 

 reacted with the usual symptoms after an incubation period of 

 six days. Both monkeys had an incubation period of five days, 

 and died of surra on the fourteenth and the fifteenth day, 

 respectively. The 2 guinea pigs likewise became infected. 



A second experiment was conducted with captured flies, surra 

 horse 343 being used in this experiment. From February 6 

 to February 10, six flies in all were allowed to bite healthy 

 horse 342 after they contaminated their proboscides with the 

 blood of surra horse 343. The blood of the latter contained 

 numerous trypanosomes upon only one occasion during the ex- 

 periment; .at other times the trypanosomes were scanty or 

 moderate in numbers. The interval between the biting of the 

 infected and the healthy horse was never more than twenty 

 seconds, and the meal was completed in from four to eleven 

 minutes on horse 342. An incubation period of nine days follow- 

 ing the last bite elapsed before the healthy horse showed evidence 

 of infection from the bites of the contaminated flies. On the 

 evening of February 19 the temperature of horse 342 rose to 

 41°. 1 C, and the blood showed a moderate number of trypano- 

 somes. Upon the following day, when the trypanosomes were 

 more numerous, blood from this animal was inoculated into 

 2 monkeys and 2 guinea pigs. The monkeys showed the first 

 signs of infection on the seventh day and the guinea pigs on 

 the eighth and ninth days. The 2 monkeys and the 2 guinea 

 pigs were alive, but still infected on March 3, 1913. 



BITING EXPERIMENTS WITH ANIMALS IN A LARGE CAGE 



An effort was made to induce flies to feed on a healthy and 

 on infected animals kept together in a large screened cage. The 

 results were negative, the flies dying in a few days when kept 

 within the inclosure. The animals used were 2 surra-infected 

 and 1 healthy carabao. The latter was separated from the 

 others by a coarse-meshed wire partition. The flies were in- 

 troduced daily into the common inclosure and were given ample 

 opportunity to bite the animals exposed. From November 9 

 to December 22, 1911, 2,087 female tabanids were liberated in 

 the cage. The animals were examined daily, and after the ex- 

 periment the healthy animal was removed and observed. Four- 

 teen months have elapsed and the exposed carabao remains 

 normal. Two guinea pigs inoculated with its blood were alive 

 and negative on April 12, 1913. 



