38 Dll DRYSDALE'S HYI'OTHESIS. 



where he stated that Tsetse-fly disease was apparently unknown. 

 The lecturer's views as to what he considered to be the exagge- 

 rated statements concerning the harmful effects of the bite of the 

 Tsetse-fly, as also of the Diptera known under the name Surrita 

 (and other variants of the same word), were identical with those 

 of Marno (vide supra). 



In 1877 Dr. Joseph Mullens [54] gave an account of an 

 interesting exp>eriment with draught oxen on the road between 

 Saadani and Mpwapwa, which seemed to have proved satisfactorily 

 that the Tsetse-fly did not occur on that section of one of the 

 possible routes to Lake Tanganyika. The same year saw the 

 publication of Thomas Baines' " Gold Regions of iSouth-Eastern 

 Africa " [55], which gave numerous details as to the occurrence of 

 Glossina morsitans in the Transvaal, with notes on the way in which 

 it may be distinguished from other flies, the efiects of its bite in 

 cattle, as summarized by Henry Hartley, a well-known elephant- 

 hunter and pioneer at that time, on the efiects of the external 

 application of ammonia as a remedy in the case of fly-bitten 

 horses, etc. Baines included mules, donkeys, sheep and goats 

 among the animals "believed to be unaflfected by the virus," 

 though he proceeds to add that mules are not always safe, and 

 that " Mr. St. Vincent W, Erskine doubts the safety of the 

 donkey on the south-east coast." From the latter remark it 

 would appear that by this time Erskine had seen fit to change 

 his ideas with regard to the efiects of the Tsetse's bite. 



In "Through the Dark Continent" [56], published in 1878, 

 Stanley mentions having encountered the Tsetse during his journey 

 down the Congo, on the islands below Rubunga. In a paper 

 by F. B. Fynney [57], which appeared in the same year, the 

 author stated that during the preceding si.x years the Tsetse had 

 disappeared from many parts of the Transvaal, formerly known 

 as Fly Country, and remarked that it was hardly necessary to 

 attach so much importance to the presence of the Tsetse as was 

 usually done, "because the fly is merely a temporary and 

 ephemeral scourge, and always disappears with the large game." 



The first definite suggestion of the true part played hy the 

 Tsetse-fly in connection with the disease which bears its name 

 appeared in 1879, in the report of an address delivered by 

 Dr. J. J. Drysdale [58] to the Literary and Philosophical Society 

 of Liverpool, where it is stated that the Tsetse-fly " may be the 

 intermediate host of some .... blood-parasite ; or it may be 

 the carrier of some infective poison. It is highly improbable 



