184 
MULTIPLICATION-FORMS OF TRYPANOSOMA 
LEW I SI IN THE BODY OF THE RAT. 
By ALFRED C. COLES, M.D., D.Sc., F.R.S.E., M.R.C.P. (Lond.). 
(With Plates X and XI.) 
During an investigation extending over several years of the forms of 
Trypanosoma lewisi, as met with in naturally infected Mus decumanus, 
I have met with many phases which I have not seen described. 
My material consisted of dead rats, killed in the immediate neigh¬ 
bourhood of Bournemouth, and brought in to me during the last ten 
years. As many of the rats had been killed some hours before I could 
examine them, it was not always possible to obtain blood from the 
peripheral vessels, but films were made from these when practicable, 
and from the heart, lungs, and other organs. These were fixed whilst 
wet with the vapour of osmic acid or iodine and stained with Giemsa. 
Coiled up Trypanosomes. In a very small percentage of these 
naturally infected rats I met with trypanosomes coiled up more or less 
in the form of a ball. Even when present they were only found in 
smears from the lung and then in small numbers. They were always 
associated with the presence of fairly numerous T. levjisi in their 
“ordinary” or “adult” form, that is trypanosomes of the same size 
and presumably the same stage of development. 
Occasionally recurved trypanosomes were encountered, in which 
the body had doubled on itself, or even pear-shaped trypanosomes. 
More generally the parasite had rolled itself into a round or oval-shaped 
body with the flagellum coiled up closely. Sometimes no definite 
flagellum could be made out, and an apparent Leishmania- like structure 
was seen enclosing a nucleus and a centrosome, but I think even in 
these cases a flagellum was present, forming the boundary of the body. 
The photomicrograph, PL X, figs. 1 to 4 and 6 to 8 (x 1500 diameters) 
shows the general appearance of these bodies. 
