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concerning: these trypanosomes, to which we have referred as 
T. divwrphon and T. vivax, should l)e most clearly stated; so that, 
whatever be the faults in our detluctions, these may be recognised 
and corrected by those to whom the necessary facilities are available. 
Owing to our protracted absence from Europe and the relative paucity 
and delay in the receipt of current scientific literature, we shall be 
precise in specifying all communications referred to, since it is not 
unlikely that at the time of writing important papers bearing on this 
particular case may have appeared in print, but will remain inaccessible 
to us for some months. 
Probably no sub-division of the Protozoa presents more difficulties 
in the way of classification than does the genus Trypanosoma Gruby, 
emended by Laveran and Mesnil in 1901 so as to exclude those 
organisms of fish which carry both an anterior and a posterior 
flagellum. On morphological grounds Liihe has created the genus 
Trypanozoon to contain only those trypanosomes parasitic in the 
blood of Mammals ; beyond this no further attempt has been made to 
classify or arrange the genus; and, indeed, any additional sub¬ 
division would be impracticable to a Zoologist. We are in a transition 
stage, when rumours of multiplication cycles, resting stages and forms 
which from their appearance are unrecognisable, even as flagellates, 
are abroad. At the present time, we have positive knowledge only of 
the well-known forms found free-swimming in the blood; and these 
presenting such close analogies to one another, offer no opportunity to 
the Protozoologist of sati.sfactorily adopting any further classification 
based on morphological features, ft is possible that the more exact 
and more strictly cytological technique which is now being employed 
m the study of these organisms may bring to light some new features 
m their structure to serve as a fixed point from which morphological 
classification can commence; but until it has been employed 
uni ormly on all known species, and critical comparisons made, it is of 
I t e more value than the older methods used both bv Zoologists and 
Pathologists. 
Any classification dependent upon a variable feature and allowing 
g ns to t e personal equation must be prone to error, and cannot 
be unquestionably accepted. Yet we find that Zoologists and 
athologists alike accept as species forms of trypanosomes 
distinguished from others on morphological grounds, r. dhmrfhon 
