206 
Enumerate Studies on Trypanosoma gambiense and Trypanosoma 
rhodesiense in Rats, Guinea-pigs, and Rabbits; Periodic 
Variations disclosed. (Preliminary Note.) 
By H. B. Fantuam, D.Sc., B.A., and J. G. THomson, M.A., M.B., Ch.B. 
(Communicated by Major R. Ross, C.B., F.R.S. Received October 15,—Read 
December 8, 1910.) 
The investigations were undertaken at the suggestion of Major R. Ross, 
under funds allotted by the Tropical Diseases Research Committee in the case 
of one of us (H.B.F.) and under the Sir Edwin Durning-Lawrence Fund in 
the case of the other (J. G. T.). 
The researches were necessary in order to, determine whether a regular 
periodic increase in the trypanosomes in the peripheral circulation of sub- 
inoculated animals occurred, like that found by R. Ross and D. Thomson 
(1910)* in a case of Rhodesian Sleeping Sickness, and whether this numerical 
cyclical development had a definite significance in the life-history of the 
parasite, which it would be necessary to consider in the case of treatment by 
drugs or other methods. Our work was done in the Liverpcol School of 
Tropical Medicine. 
The trypanosome from the patient suffering from Sleeping Sickness 
contracted in Rhodesia was found by Stephens and Fantham (1910)+ to 
exhibit a marked morphological peculiarity in the presence of a posterior 
nucleus, and for this parasite the name 7’. rhodesiense was suggested by them. 
We have also used an old laboratory strain of 7. gambiense. 
In all cases a definite number of trypanosomes were inoculated. The 
inoculation was made subcutaneously in rats, intra-peritoneally in guinea-pigs 
and rabbits. The peripheral blood of these animals was then examined daily 
at the same hour, that is to say at regular intervals of 24 hours. 
The technique employed was that elaborated by Rh. Ross and D. Thomson 
in their study of the patient W. A., namely, that a known quantity of blood 
(1 cubic millimetre divided into quarters) was taken and the parasites therein 
very carefully counted. In counting the thick films, an Ehrlich eyepiece was 
used, after the films had been dehemoglobinised, fixed with absolute alcohol, 
and stained by the Romanowsky method. When the parasites were very 
numerous, it was necessary to spread the quarter cubic millimetre of blood 
over a larger square area than usual, and to use a small diaphragm in the 
* “Roy. Soc. Proc.,’ B, vol. 82, pp. 411—415. 
t ‘Roy. Soc. Proc.,’ B, vol. 83, pp. 28—33. 
