219 



The Trypanosome causing Disease in Man in Nyasaland. — 

 The Naturally Infected Dog Strain. Part IV. — Experiments 

 on Immunity. 



By Surgeon-General Sir David Bruce, C.B., E.R.S., A.M.S. ; Major A. E. 

 Hamerton, D.S.O., and Captain D. P. Watson, R.A.M.C. ; and Lady 

 Bruce, R.R.C. (Scientific Commission of the Boyal Society, Nyasaland, 

 L912-14.) 



(Received May 5, — Read June 25, 1914.) 

 Introduction. 



The following experiments were undertaken to find out whether the 

 Naturally Infected Dog strain of the trypanosome causing disease in man 

 in Nyasaland would protect against the other strains. These different 

 strains have been described in previous papers as the "Human," the " Wild 

 Game," the "Wild Glossina morsitans," " Zululand, 1913," etc., and here 

 they will be known by the same names. " Human " will therefore mean a 

 strain of this species of trypanosome coming from man, " Wild G. morsitans " 

 from a tsetse fly, and so on. 



These immunity experiments were necessarily one-sided, as it was, with 

 three exceptions, only animals which had recovered from the weaker 

 Naturally Infected Dog strain which were available. 



There are practically no recoveries from the Human and other strains. 

 One goat apparently recovered from the Mzimba strain, and a goat, monkey 

 and dog from the Wild G. morsitans strains, and are included. 



There are, therefore, no completed cross-inoculation experiments — or at 

 least only one unsatisfactory one, Experiment 17 — as would have been 

 carried out if material had been forthcoming. 



It will be seen from the following experiments that the Naturally Infected 

 Dog strain failed to immunise animals against the Human, Wild G. morsitans, 

 and Zululand, 1913, strains ; but it is not known whether these strains, on 

 the other hand, would have immunised animals against the Naturally Infected 

 Dog strain or not : — 



