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THE LIFE HISTORY OF TRTPANOSOMA 
LEWISI 
BY 
J. E. SALVIN-MOORE 
PROFESSOR OF EXPERIMRSTAI- AND PATHOLOGICAL CYTOLOGY, UNIVERSITY OY 
LIVERPOOL • 
ANTON BREINL 
LIKECrOR OF THE RUNCtiRN RESEARCH l.AIIORATORIES, LIVERPOOL SCHOOL OF 
TROPICAL MEDICINE 
AND 
EDWARD HINDLE 
LEMOSSTRATOR IN THE RUNCORN RESEARCH LABORATORIES, LIVERPOOL SCHOOL 
OK TROPICAL MEDICINE 
{Received for publication 5 May^ 1908) 
The Trypanosomes, so far as at present known, are universally 
parasitic organisms inhabiting the blood and the body fluids of a 
variety of animals. In certain cases, the presence of trypanosomes 
produces the most marked pathological results. In others, the 
parasites are apparently quite harmless. Moreover, the same 
trypanosomes which are pathogenetic with respect to one animal, are 
often non-pathogenetic in the case of others. There is a tendency 
at present to attempt to draw a distinction in a classificatory sense 
between the so-called pathogenetic, and non-pathogenetic forms of 
trypanosomes. But even from the facts just referred to, it would 
seem to be clear that any such method of grouping can have but 
little real significance, and is more likely to entirely mislead enquiry 
than to throw any fresh light upon the singular and, morphologically 
speaking, closely knit group of organisms which the trypanosomes 
undoubtedly constitute. 
There appear, as a matter of fact, to be two main 
groups of problems connected with the trypanosomes at the 
present time. The first is constituted by our ignorance of the 
complete features of the developmental cycle of even any well-known 
and characteristic representatives of the group. The second by the 
present impossibility of determining to what group of non-parasitic 
