484 Cattle as a Reservoir of the Virus of Sleeping Sichiess. 



flagellates. The alinieutary contents of one of these flies were injected into a monkey, 

 and after an incubation period of 13 days Trypanosoma gamhiense appeared in its blood. 

 Res ult. — Posi tive. 



Condusion. — Laboratory-bred tsetse flies can be infected by feeding them on cattle 

 infected with Sleeping Sickness, and afterwards the disease can be transmitted to healthy 

 animals by means of these flies. 



V. Bo Cattle, when Living in the Flij-area, act%Mlly carry the Virus of 



Sleeping Sickness ? 



About seventeen cattle from various sources were examined with this point 

 in view. Not all these cattle could be proved to have been exposed to the 

 bites of Glossina 2)alj)alis, but most of them came from places where these 

 flies are plentiful. One was positive. 



Experiment 1633. 



This cow came from the island of Kome, in Lake Victoria, where human Sleeping 

 Sickness is prevalent and where Glossina 2>aJpalis abound. 



Trypanosoma gamhiense was found in its blood by microscopical examination, and when 

 3 c.c. of the blood were injected under the skin of a monkey the animal developed 

 Sleeping Sickness after an incubation period of seven days. 



Conclusion.- — This experiment proves that cattle in their natural state, and apparently 

 in good health, may harbour the virus of Sleeping Sickness. 



General Conclusions. 



It has been proved by experiment that cattle may act as a reservoir of 

 the virus of Sleeping Sickness, and that healthy animals may be infected from 

 them by means of Glossina palpalis. 



It has also been proved that cattle in the fly-area do naturally harbour 

 Tri/panosoma gavibicnsc. 



It is, therefore, possible that the cattle and antelope living in the fly-area 

 may act as a reservoir, and so keep up the infectivity of the Glossina palpalis 

 for an indefinite ])eriod, l)ut there is no proof up to the present that this 

 actually takes place in Nature. 



