XVIIl] GENERAL ACCOUNT 329 



constant presence in the blood of an intusorian parasite — a 

 trypanosome." 



It is generally supposed that Bruce employed Glossina 

 morsitans in these transmission experiments, but, according to 

 Austen, from a consideration of the description and figures 

 given in Bruce's Report on the tsetse-fly disease, or nagana, in 

 Zululand, there can be little doubt that G. pallidipes was the 

 species employed. 



T. brucei is one of the best known of all the trypanosomes, 

 as a dog infected with the parasite reached England in 1898, 

 and subsequently was sent to most of the laboratories of 

 Europe. As a result this parasite is the one most often employed 

 in treatment experiments and other observations on the 

 biology of trypanosomes under experimental conditions. 



The disease is widely distributed in Africa, where, in addition 

 to Zululand, it has been recorded from the basins of the Limpopo 

 and Zambesi, Nyasaland, Northern Rhodesia, German and 

 British East Africa, Uganda, Bahr el Ghazal, and in the region 

 of the White Nile. 



It is also possible that the disease may occur in Somaliland 

 and Galla, for the trypanosome causing the camel disease 

 known as Aino is indistinguishable morphologically from 

 T. brucei. 



Nagana is one of the most deadly of all trypanosomiases 

 and the majority of animals succumb to the infection after a 

 comparatively short illness. 



With regard to the virus as it occurs in the laboratories of 

 Europe, Laveran and Mesnil divide the mammals into three 

 groups according to their susceptibility. 



" (i) Animals in which nagana produces an acute infec- 

 tion : mice, rats, marmots, hedgehogs, dogs and monkeys. 



(2) Animals in which nagana produces a sub-acute 

 infection : rabbits, guinea-pigs, dormice, horses, donkeys, 

 mules and pigs. 



(3) Animals in which nagana produces a chronic infection : 

 cattle, goats and sheep." 



In nature the disease affects horses, ruminants and dogs, 

 and also the wild game, such as antelopes, waterbuck, etc., 



