INTRODUCTION. 



More than fifty years have elapsed since Gordon Gumming drew 

 the attention of all who were interested in African travel and 

 adventure to the fatal effects upon horses and cattle of the bite 

 of "the famous fly called 'Tsetse.'" "With the publication of 

 successive volumes containing the experiences of explorers, and 

 of elephant-hunters and sportsmen who gradually began to pene- 

 trate into what were then the happy hunting-grounds between 

 the Vaal River and the Zambesi, the tale of loss and disaster due 

 to the Tsetse was rapidly swelled ; and it was not long before 

 these insignificant-looking insects were recognised as constituting 

 a barrier more formidable to the explorer and the colonist than 

 almost any other. Thus the general interest taken in the genus 

 which forms the subject of this book has never slackened, and 

 *' the Tsetse-fly " — for it is a common error to speak as though 

 there were but a single species — is known by name to thousands 

 of people who have no idea as to what a specimen is like. 



For a long time the Tsetse was believed to be directly 

 responsible for the havoc caused by its bite, the prevailing 

 opinion being that it elaborated within itself a subtle poison 

 which when injected into domestic animals occasioned their more 

 or less speedy death. It was not until the year 1895 that the 

 brilliant researches of Lieut.-Colonel Bruce, in Zululand, showed 

 that this idea was mistaken, <and that the part played by the 

 Tsetse-fly in producing the disease which bears its name was in 

 the main analogous to the role of certain mosquitoes in the dis- 

 semination of malarial fever among human beings. Bruce proved 

 that the Tsetse is merely the carrier of a haematozoon or blood- 

 parasite, now known as Trypanosoma hrucei, Plimmer and 

 Bradford,* which appears to live normally in the blood of many 



* " Proceedings of the Royal Society of London." Vol. LXIV, 

 (August 31, 1899), p. 280. 



