108 



But science has not yet pronounced an opinion, while the views of 

 entomological specialists show great divergence. What is needed at 

 the moment is not hasty and dangerous measures, but an exhaustive 

 study of the question. 



The experiment indicated in the subjoined extract from a paper by 

 Mr. LI. Lloyd (89) seems well worth' trying. 



" Further evidence of the relation of the fly to the larger mammals," 

 writes Mr. Lloyd, " could be obtained by compelling it, under as natural 

 conditions as possible, to attempt to support itself on a diet of the 

 smaller mammals, birds and reptiles. The following experiment is 

 therefore suggested. A large fly-proof cage, of some such dimensions 

 as 100 yds. long by 50 yds. wide and 7 ft. high, would be constructed 

 on a piece of country favoured by tsetse-fly and in which breeding 

 places were known to exist. Into this cage would be introduced a 

 number of small mammals and birds, the insectivorous species being 

 excluded. A large number of tsetse would then be set free in the cage 

 and daily observations as to their increase or decrease would be made 

 by a well-veiled observer. At the end of twelve months it should be 

 known if the fly is able to continue its species on such a fauna. In this 

 event, increase should occur, since there would be few enemies in the 

 cage. If the numbers of the fly decreased, the experiment would be 

 repeated with the introduction of a few young antelopes, goats or sheep 

 into the cage, and similar observations would be made over the same 

 period. If the increase occurred under these new conditions, the 

 dependence of the fly on the larger mammals would be made clear. 

 The first of these experiments would also yield evidence as to whether 

 the smaller mammals could act as the reservoir of the pathogenic 

 trypanosomes of man and domestic stock." 



OUTBREAKS OF CATTLE TRYPANOSOMIASIS APPARENTLY DUE TO 

 BITING FLIES OTHER. THAN Glossina. More than a decade ago, Bruce 

 and his collaborators in Uganda observed seasonal outbreaks of trypano- 

 somiasis among cattle, under circumstances pointing to the agency 

 of Tabanidae (Horse-flies) as disseminators. The subject is obviously 

 one of no little importance to stock-breeders and cattle-owning natives 

 in areas not directly threatened by Tsetse-fly, and in recent years 

 several writers notably Mr. R. W. Jack in Southern Rhodesia have 

 devoted some attention to it. The more important statements and 

 conclusions contained in these later papers are summarised in the 

 following paragraphs. 



Jack (69), who gives details of an outbreak of trypanosomiasis in 

 1916, on a farm on the Sikombella River, Southern Rhodesia, considers 

 the case in question as practically amounting to proof that trypano- 

 somes of the type of T. pecorum can, under natural conditions, be 

 transmitted from an infected to a healthy ox by some agency apart 

 from a Tsetse-fly. In a subsequent paper (70) this author furnishes 

 detailed accounts of a number of similar outbreaks, three being among 

 cattle, and two among pigs on isolated farms in the same region, some 

 miles away from a belt of G. morsitans. From these he concludes that, 

 given the necessary conditions, transmission of the disease may take 

 place, and has occurred more often than has generally been recognised, 

 in the absence of Tsetse-fly. Such transmission, which is mechanical 

 and direct not cyclical, is considered to be most probably effected by 

 Tabanidae, Stomoxys cakitrans, Lypewsia and mosquitos, and it is not 

 necessary to infer that ability to disseminate the disease in this way is 



