ON THE ZOOLOGICAL STATUS OE THE POLYMORPHIC 
MAMMALIAN TRYPANOSOMES OE AFRICA AND THEIR 
RELATION TO MAN. 
By H. LYNDHUBST DUKE, O.B.E., M.D., D.T.M. & H. (Camb.). 
( Bacteriologist , Uganda Protectorate.) 
(With 1 Text-figure.) 
CONTENTS. 
PAGE 
Introduction.352 
Part I. Reflections on the aetiology of the Uganda epidemic.357 
(a) Lack of definite evidence of occurrence of human trypanosomiasis in Uganda. 
lake-shore fly areas before the epidemic.357 
(b) Acute type of the disease in the early days of the epidemic.359 
(c) Direct transmission hypothesis as an explanation of the virulence of the epidemic 359 
(cl) Role of cyclically infected flies in the spread of the epidemic.360 
Part II. Infectivity of wild lake-shore flies, 1920-21 . 362 
(a) Feeding experiments with wild flies.362 
( b) Dissections of wild flies.364 
(c) Glossina morsitans dissections in Uganda and Nyasaland.365 
(d) The trypanosomes of palpalis regions in Uganda and elsewhere .... 365 
Part III. Animal reactions of the Uganda lake-shore polymorphic trypanosomes . . 366 
(а) Wild-fly, mainland, and Damba Island strains.366 
(б) Examination of situtunga on the Sesse Islands.368 
(c) Damba antelope strain, 1920 369 
(d) Posterior-nuclear forms.370 
(e) Action of human serum ... .371 
(/) Behaviour of mangabey (Cercocebus albicjenu sub. sp.).371 
( g) Infection of chimpanzee.372 
(/*) Conclusions. 373 
Part IV. Direct-transmission experiments .... ... 374 
Conclusions.376 
Part V. Experiments with laboratory-bred flies and the lake-shore and human strains. 376 
(a) Meteorological conditions at Entebbe and Mpumu.377 
(b) Tables of fly experiments and discussion of same.377 
(c) Failure to find flagellates in flics held to be infective.384 
(d) Effects of different kinds of blood on the developing flagellates .... 385 
(e) Conclusions as to the effect of reptile blood on developing trypanosomes . . 387 
Part VI. General review and summary.387 
References.396 
INTRODUCTION. 
The polymorphic trypanosomes of mammals have commanded a considerable 
amount of attention during the last 25 years. Bruce’s classical work on Nagana 
in Zululand—conducted in 1895 and 1896—stands out as a splendid example 
