CONCERNING GL0S8INA MORSITANS. 149 



Where flies are plentiful their pi*e£erences, if any, might be ascertained by 

 observing to what extent they are attracted by the carcases of different 

 animals. The smaller animals should be specially observed, e, r/., guinea- 

 fowl, hares, jackals, baboons, duiker and pig. 



Attractive and repellent suhstances. — There is ample scope for experiment 

 in the hope of discovering some substance which is specially attractive to 

 ihese flies ; if such could be found, it would be of inestimable value, as it 

 would enable us to trap and destroy large numbers of the insects. Maldonado's 

 i:rap {vide Bull. Ent. Res. part 1, p. 85) should be systematically tested. 

 An efficient dressing may yet be discovered which will deter tsetses from 

 biting stock for a serviceable period ; no really exhaustive experiments liaA^e 

 yet been made for this purpose. 



Miscellaneous. — Montgomery says that tsetse-flies will plague a moving- 

 man or animal, but if he stops they wdll leave him. Is this generally so? 

 If it is, what is the reason ? 



When notes on the bionomics of the fly are sent in, exact information 

 should be given as to the climatic and other conditions : if the rains have 

 been falling, if so, how long; if not, w^hen they will begin ; whether tlie 

 grass has been burnt ; and so forth. 



Observers who are noting the habits, life-history, etc. of tsetse-flies must be 

 -quite certain of the species with which they are dealing, ^. ^., whether it is 

 niorsitans or pallidvpes or a mixture of more than one species. Neglect of 

 this precaution may account for many discrepancies in the observations of 

 modern as well as ancient authors. It is not improbable, for instance, that 

 tl;e habits of morsitans i\nd pallidipes differ in some important particulars. 



II. The Investigation of Pathogenic Trypanosomes in 

 Wild Animals. 



Necessity for animal inoculation. — In the investigation of this problem it is 

 uot enough to examine blood-smears from all the animals in any locality. 

 The parasites may be so rare that prolonged search through many slides will 

 fail to discover a single one. The much more delicate method of animal 

 inoculation must be used. The experiments of Bruce in Zululand demon- 

 strated this. With precautions against their becoming infected in natural 

 ways he injected the blood of forty-five wild animals into healthy dogs. Of 

 these eleven became infected. In three cases only was he able to find 

 trypanosomes in the blood of wild animals by direct examination. He writes; — 

 ■^' The parasites were few and far between, and it was only by long and patient 

 searching that they could be found at all.'^ The investigations of others 

 ( Dutton and Todd ; Montgomery and Kinghorn ; Brand) go also to show that 

 animal inoculation must be practised. By this or the direct method, in 

 -Zululand the blood of buffalo, hy<ena, and five species of antelope was shown 



