Strain of T. brucei from Zululand. 



497 



1913 strain killed one horse in 35 days. The former strain killed five dogs 

 in an average of 21 days, the latter four clogs in an average of 19 days. 



Taking these various arguments into consideration, it may be assumed that 

 the strain of trypanosome which forms the subject of this paper belongs to 

 the species T. brucei, a well-marked dimorphic type of trypanosome. 



The object of this paper is to describe as fully as possible the morphology 

 of this new strain of T. brucei from Zululand, in order to try to prove its 

 identity with the trypanosome causing disease in man in Northern and 

 Southern Ehodesia, Nyasaland, and German and Portuguese East Africa. 

 The importance of this cannot be overrated. It bas been the habit in the 

 past to consider T. brucei harmless to man, but if the above conjecture proves 

 to be true, then all Glossina morsitans areas where wild game and T. brucei 

 co-exist must be looked upon as dangerous. Evidence is accumulating 

 that this is so. Eecently two Europeans have fallen victims to the tsetse- 

 fly disease in the Sebungwe district in Southern Rhodesia, a remote, savage, 

 unfrequented spot swarming with game and G. morsitans. This year also — - 

 1913 — as had been anticipated, several cases have been found in the Nyasaland 

 fly-areas to the north and south of the " Proclaimed Area," one case occurring 

 in a native village within a few miles of Zomba, the official capital. 



In future papers, the Susceptibility of Animals to this Strain, its Develop- 

 ment in G. morsitans, Sera Reactions and Cross Inociilation Experiments will 

 be dealt with. 



I. Morphology of T. brucei, Zululand Strain, 1913. 



A. Living, Unstained. 



In the living and unstained preparations the dimorphic characteristics of 

 this species can be readily made out. The parasites are actively motile but 

 with restricted translatory movement. 



B. Fixed and Stained. 



The blood films were fixed, stained and measured as previously described 

 in the ' Proceedings.'* 



Length. — -The following table gives the length of this trypanosome as found 

 in the monkey, dog, guinea-pig and rat, 1000 trypanosomes in all. 



* B, vol. 81 pp. 16 and 17 (1909). 



