188 
Trypanosoma lewisi 
mass with three nuclei, three centrosomes and three flagella; Fig. 25, 
irregular mass with four nuclei, four centrosomes and four flagella. 
The remaining figures show crithidial forms many of which are 
dividing, whilst Fig. 31 represents a very small trypanosome. Figs. 
23 to 34 were from the heart or lung blood. 
I examined very carefully numerous smears from the lung of this 
rat but I could find no coiled up trypanosomes or multiplication cysts 
such as I have previously described. 
Note. 
Since the above was written I have found, after very prolonged 
examination, another group of tiny trypanosomes in the film made 
from Rat A, and also one group in Rat C resembling precisely 
Figs. 5 and 13. 
I have since June 1st examined 86 more rats, by far the greater 
number of which were quite young specimens. Of these 55 came from 
the town and only two were infected, whilst in 30 from the country 12 
contained trypanosomes. In three of the latter I found T. lewisi in 
all stages of division in the blood of the peripheral vessels as well as in 
many of the internal organs. These were small rats measuring about 
five to six inches in length. In two of these coiled up trypanosomes 
were found sparsely in the lung, and in one measuring only five inches 
numerous examples were seen in the fiver. In a fresh cover-glass 
preparation made from the liver the coiled up trypanosomes appeared 
to be in a perfectly colourless cyst, about the size or a little larger than 
a red corpuscle, and the enclosed parasite was twisting and turning 
about very actively in its apparent envelope, but in no case did I see 
one escape or unroll. 
In the heart blood of a rat about seven inches long I found that 
many of the trypanosomes were arranged in rosettes of auto-agglutinated 
parasites, a condition I have once before noticed. 
REFERENCES. 
Coles, A. C. (v. 1914). Blood Parasites found in Mammals, Birds and Pishes in 
England. Parasitology, vn, 17. 
Delanoe, M. and Mme Pierre (7. x. 1912). Sur les Rapports desKystes de Carini 
du Poumon des Rats avec T. lewisi. Comp. Rend. Acad. Sci. clv, 658-660. 
Laveran et Mesnil (1912). Trypanosomes et Trypanosomiases, p. 263. 
Minchin E. A. and Thomson, J. D. (i. 1915). The Rat trypanosome, Trypanosoma 
lewisi, in its relation to the Rat Flea, Ceratophyllus fasciatus. Quart. Journ. 
Micr. Sci. lx. Part 4. 
