417 
ENUMERATIVE STUDIES ON 
TRTFANOSOMA GAMBIENSE AND 
TRYPANOSOMA RHODESIENSE IN 
RATS, GUINEA-PIGS, AND RABBITS; 
PERIODIC VARIATIONS DISCLOSED' 
BY 
H. B. FANTHAM, D.Sc., B.A., 
AND 
J. G. THOMSON, M.A., M.B., Ch.B. 
{Received for publication 15 October , 1910 ) 
CONTENTS 
Introduction . 
Outline of Methods . 
Enumerations in Rats . 
(a) Trypanosoma rhodesiense — 
I. Rats exhibiting periodic variation . 
2 . Rats exhibiting continuous rise in the number of parasites 
(b) Trypanosoma gambiense — 
1. Rats exhibiting periodic variation 
2. Rats exhibiting continuous rise 
Comparison of the two strains in Rats 
Enumerations in Guinea-pigs ... ... . 
Enumerations in Rabbits . . 
Comparison of the effects of the Trypanosomes on the various hosts 
Explanation of the periodic increase and decrease in the numbers of 1 trypanosomes 
in the peripheral blood of the ho 9 t . 
Summary . 
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INTRODUCTION 
The results recorded in this memoir were obtained chiefly irom 
investigations on animals — rats, guinea-pigs and rabbits— 
sub-inoculated from a case of Rhodesian sleeping sickness recentl) 
studied by Major R. Ross and Dr. D. Thomson in the Royal 
Southern Hospital, Liverpool. 
1 he investigations were undertaken at the suggestion of Majoi 
Ross, under funds allotted by the Tropical Diseases Resear ch 
* An abstract of this paper was read before the Royal Society on December 8. ) 
and published in Proc. Roy. Soc.. B. Vol. I.XXXIII. pp- 206-211. 
AA 
