423 



The Morphology of the Trypanosome Causing Disease in Man 

 in Nyasaland. 



By Colonel Sir David Bruce, C.B., F.B.S., A.M.S.; Majors David 

 Harvey and A. E. Hamerton, D.S.O., E.A.M.C. ; Dr. J. B. Davey, 

 Nyasaland Medical Staff; and Lady Bruce, B.B.C. 



(Scientific Commission of the Royal Society, Nyasaland, 1911—12.) 



(Eeceived May 24,— Eead June 6, 1912.) 



[Plates 11 and 12.] 



Introduction. 



This species, like Trypanosoma brucei and T. gambiense, is characterised 

 by showing two distinct forms — the long and slender, and the short and 

 stumpy. These are not sharply divided from one another, but are 

 connected by intermediate forms, so as to form an unbroken series, or curve, 

 from the shortest to the longest. 



This strain of the trypanosome was obtained from a native woman 

 suffering from " Kaodzera," the so-called Sleeping Sickness of Nyasaland. 



A. Living, Unstained. 



The movements of the Nyasaland trypanosome resemble T. brucei and 

 T. gambiense in being non-translatory either in fresh blood or in dilutions 

 with citrate solution. Under dark background illumination, however, with a 

 higher degree of dilution, some translatory movement is seen, the trypanosomes 

 swimming slowly across the field. 



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 man, monkeys, goats, sheep, dogs, guinea-pigs, and white rats — 1220 

 trypanosomes in all. From this it will be seen that it measures, on an 

 average, rather more than T. brucei or T. gambiense, but the difference is so 

 small as to be probably of no value as a means of separating these species. 



* 'Roy. Soc. Proc.,' 1909, B, vol. 81, pp. 16 and 17. 



