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The Infe-History of Trypanosoma gambiense and Trypanosoma 
rhodesiense as seen in Rats and Guinea-pigs. 
By H. B. Fantuam, D.Sc. Lond., B.A. Cantab., A.R.C.S. 
(Communicated by Prof. Major R. Ross, C.B., F.R.S. Received October 15,— 
Read December 8, 1910.) 
[PuatE 15.] 
Introduction. 
The researches recorded in this paper were undertaken at the suggestion 
of Major Ross, who wished me to investigate the parasitological aspect of 
the numerical cyclical development discovered by him and Dr. D. Thomson 
(1910) in the trypanosome occurring in a patient suffering from Sleeping 
Sickness contracted in Rhodesia, particularly as regards the possible 
connection of the latent bodies of Salvin-Moore and Breinl (1907) with 
that cycle. The investigations have been conducted in the Liverpool School 
of Tropical Medicine, under a grant from the Tropical Diseases Research 
Fund. 
A complete and generally accepted life cycle of Trypanosoma gambiense 
has yet to be written. The following paper is offered as a contribution to 
the solution of this difficult problem, and deals with that portion of the 
life history of the parasite which takes place in a Vertebrate host. 
The sub-inoculations in animals—rats and guinea-pigs—recorded herein 
were made from a patient suffering from Rhodesian Sleeping Sickness in 
Prof. Ross’s clinic in the Royal Southern Hospital, Liverpool. The 
trypanosome from this source showed a marked morphological feature in 
the possession of a posterior nucleus in some forms, and for this parasite 
the name 7. rhodesiense has been suggested by Stephens and Fantham 
(1910). A laboratory strain of 7. gambiense was also used in these 
investigations for comparison. 
Special attention has been paid to the observation of the lwing parasite, 
as well as to stained preparations. 
Methods. 
Fresh preparations of 7. gambiense and T. rhodesiense were made from 
blood taken aseptically from animals, namely, tame rats and guinea-pigs. 
The blood was kept in sealed cover-slip preparations, at or below blood heat 
(25° to 37° C.), and also at laboratory temperature. The blood was some- 
