Sleeping Sickness Studied by Precise Enumerative Methods. 411 





No. of 



No. of 





bacteria m 



non-phagocytic 





50 cells. 



cells. 



Experiment 1. 







A. Serum saline + normal leucocytes + -S. jBara<y^Ao«M« jB. ... 



230 



2 



B. Serum bacterial extract from B. paratyphosus B. + normal 



32 



23 



leucocytes + B. paratyphosus B. 







C. Serum bacterial extract from B. paratyphosus B. diluted 



492 



0 



1/10 + normal leucocytes + B. paratyphosus B. 







"RvnpriTTiPTit. 









117 



5 





181 



9 



B. Serum bacterial extract from J. ^y^AoiM* diluted 1/10 + 



153 



4 



normal leucocytes + B. prodiyiosus 







Serum bacterial extract from B. typhosus diluted 1/10 + 



372 



0 



normal leucocytes + B. typhosus 







X ' 



A Case of Sleeping Sickness Studied by Precise Enumerative 

 Methods : Regular Periodical Increase of the Parasites 

 Disclosed. 



By Major EoNALD Eo.ss, F.E.S., and David Thomson, M.B., Ch.B., D.P.H. 



(Received May 2,— Read June 16, 1910.) 



Prefatory Note hi/ R. Ross. — For a long time it has appeared to me that 

 much light might be thrown on infectious diseases, immunity and treatment, 

 by more exact enumeration of the infecting organisms, and that we might 

 even be able ultimately to apply mathematical reasoning to the study of 

 these subjects. In 1903* I elaborated a method of blood examination, 

 called the thick-film iwocess, which enables us to detect small organisms in 

 the blood about twenty times more easily than in ordinary preparations ; 

 but for the lack of the necessary assistance I was long unable to apply the 

 method to the laborious enumeration of such organisms. Recently, however, 

 the Advisory Committee for the Tropical Diseases' Research Fund has 

 placed considerable funds at the disposal of the Liverpool School of Tropical 

 Medicine for the study of cases in the tropical ward of the Royal Southern 

 ♦ ' Lancet,' January 10, 1903, and Thompson Yates Reports, vol. 5, Part I, 1903. 



