A. C. Coles 
187 
size killed 20. vm. 1914. Trypanosomes of adult size were moderately 
numerous in the blood and coiled up trypanosomes were also present 
in the lung. 
These three spheres therefore were met with only in two rats, in one 
case in the blood from the heart and in the other in the lung blood, but 
in both animals coiled up trypanosomes were found in the smears made 
from the lung. 
As to the nature of these bodies, they seem to be small Leishmania- 
like structures consisting as they do of a number of small nuclei each 
with a centrosome, and apparently associated with the presence of 
coiled up trypanosomes. It seems to me highly probable that multi¬ 
plication of T. lewisi does occur in the lungs and that possibly the 
trypanosomes become coiled up, lose their flagellum, and the nucleus 
and centrosome undergo repeated division until a cyst or sphere of 
multiplication is produced. 
Apparently I have found in the lung and heart blood of naturally 
infected rats many of the stages which Minchin and Thomson (1915) 
have described and illustrated in their monumental work on the stages 
of T. lewisi in the rat flea. Thus I have seen the recurved, the pear- 
shaped, the coiled up trypanosomes and probably spheres, “the final 
stage of intracellular multiplication.” 
Prof. Minchin, to whom I have sent photomicrographs, but who has 
not actually seen my preparations yet, says: “ They establish definitely, 
as it seems to me, what has been asserted and denied again, namely 
that T. lewisi has a stage in the lung,” and “there is no doubt that 
your photos show true T. lewisi and not Pneumocysts.” 
Multiplication of T. lewisi. It is I believe very exceptional to find 
any but the ordinary fully developed T. lewisi in the wild naturally 
infected rat. Laveran and Mesnil (1912) state: “Chez la plupart des 
rats d’egouts infectes naturellement et, en general, depuis assez long- 
temps, on chercherait en vain des formes de multiplication.” 
In the very large number of rats whose blood I have examined I 
had never succeeded in finding the multiplication stages. Thinking 
the matter over I came to the conclusion that I must limit my attention 
to quite young rats, and at last I was fortunate enough to find a small 
young rat (18. ix. 1914) in which all the stages were evident. 
Trypanosomes varying greatly in size, forms dividing by equal and 
unequal binary fission and trypanosomes with very long posterior end 
were seen. 
In addition to these were the following types: Fig. 23, irregular 
