Bruce and colleagues[99] have quite recently (June, 1914) described the development of a Zululand strain of _T. brucei_ in _G. morsitans_. The tsetse flies were bred out in Nyasaland. In vertebrate blood the _brucei_ strain was polymorphic. The development was like that found for _T. gambiense_ in _G. palpalis_ (fig. 30), and by Bruce and colleagues for _T. rhodesiense_ in _G. morsitans_ in Nyasaland. Long trypanosomes were found in the proventriculus of the tsetse. Crithidial, rounded or encysted, and immature “blood forms” occurred in the salivary glands; and finally infective, stumpy, “blood forms” were differentiated in the salivary glands. The period of development of _T. brucei_ in _G. morsitans_ takes about three weeks, and then the fly becomes infective. Bruce believes that _T. rhodesiense_ of Nyasaland and _T. brucei_ of Zululand are the same, their cycles of development in _G. morsitans_ being “marvellously alike.” (But see Laveran, p. 80.) [99] _Proc. Roy. Soc._, B, lxxxvii, p. 526. _T. brucei_ has been cultivated with difficulty by Novy and MacNeal, using blood agar. The best treatment for nagana is arsenic in some form. It is probable that more than one trypanosome has been confused under the name _T. brucei_, more especially as the occurrence of many species of trypanosomes in various animals in Africa was not suspected until comparatively recent times. It has been shown by Stephens and Blacklock (1913) that the original Zululand strain of _T. brucei_ was monomorphic, while the organism sent from Uganda, and at the time believed by Bruce to be the same as the Zululand trypanosome, has been found to be polymorphic, with morphological resemblances to _T. rhodesiense_. Stephens and Blacklock[100] have suggested the name _T. ugandæ_ for the polymorphic trypanosome, which, however, has marked resemblances with *Trypanosoma pecaudi*, and they are, perhaps, identical. _T. pecaudi_ was the name given by Laveran[101] in 1907 to the causal agent of “baleri” in equines and sheep in the French Sudan. _T. pecaudi_, which is dimorphic, is widely distributed in Africa. An extremely small number of both _T. pecaudi_ and _T. ugandæ_ have been shown to possess posterior nuclei. _T. pecaudi_ is transmitted by various species of _Glossina_, and is said to develop in the gut and proboscis of the fly. [100] _Proc. Roy. Soc._, B, lxxxvi, p. 187. [101] _C.R. Acad. Sci._, cxliv, p. 243. On the other hand, Bruce and colleagues (1914), examining a strain sent from Zululand in 1913, state that _T. brucei_ is polymorphic. Bruce (1914) suggests that passage through laboratory hosts has influenced and altered the morphology of the parasite. *Trypanosoma evansi*, Steel, 1885. Syn.: _Spirochæta evansi_, Steel, 1885; _Hæmatomonas evansi_, Crookshank, 1886; _Trichomonas evansi_, Crookshank, 1886.