16 THE SOCIETY FOE THE PEESEEYATION OF 



ments cannot, however, be regarded as in any way supporting the 

 idea that tsetse-flies could continue to exist if the supply of blood 

 in some form or other were absolutely cut off. Both mosquitoes 

 and horse-flies belong to families very much more primitive and 

 less specialised than the Muscidfe, of which the genus Glossina is 

 in many respects the most specialised representative. It is not un- 

 reasonable to regard the specialisation in this case as being ex- 

 hibited in the diet as well as in the bodily structure and remarkable 

 mode of reproduction, which makes it in the highest degree un- 

 likely that plant-juices can supply tsetse-flies with all that is 

 necessary for the support of themselves and their offspring. 

 Another indication of specialisation, which, however, the tsetse- 

 flies exhibit in common with other blood-sucking Muscidae, is seen 

 in the fact that both flexes suck blood, whereas in the case of all 

 other phlebotomic Diptera, with the possible exception of Phleho- 

 fomus and the still more specialised Hippoboscidffi (forest-flies, &c.), 

 the habit is confined to the females. 



The Alleged Dependence of Tsetse-flies upon Big Game, 



Having thus made candid admission of the fact that blood is 

 indispensable to tsetse-flies, we will now see to what extent recent 

 observations support the oft-repeated assertion or assumption that 

 the animals included in the comprehensive designation game are 

 necessarily the source of supply. Before entering upon this ques- 

 tion, however, it seems advisable to say a few words by way of 

 personal explanation. Prior to the year 1903, when the author's 

 * Monograph of the Tsetse-flies ' was published, by far the greater 

 portion of the recorded observations upon the subject of the rela- 

 tions between tsetse and big game referred solely to Glossina 

 viorsitans, and to Africa south of the Zambesi, where, as will be. 

 shown later in speaking of tsetse and buffaloes, conditions at the 

 time at which many of the observations were made were in some 

 respects of a special character. Having then little else to go upon 

 when writing of the habits of tsetse-flies in general, and being 

 perhaps unduly influenced by a suggestion made fifty years ago 

 by Livingstone,^ I was led to make what has since proved to be a 

 far too sweeping generalisation as to the dependence of tsetse-flies 

 upon big game.- The statement in question is the more to be 

 regretted since it was naturally used by Mr. Hastings as an argu- 

 ment in support of his suggestion, referred to above, for the experi- 

 mental abolition of game within a selected fl)^ district. But, just 

 as the discovery that the blood-parasites that produce malarial 

 fever in man are disseminated by the bites of certain mosquitoes 



^ David Living-stone, Missionary TravrU and Researelies in Sovth Africa 

 (London : John Murray, 1857), p. 83. 



■^ Vide Austen, Monograjdi of ilie Tsptsc-ilien (London : Printed by Order 

 of the Trustees of the British Museum, 1903), p. 12. 



