APPENDIX. 357 



nation, which shows that in dying the somewhat ribbon- 

 like parasite has become doubled on itself. 



Owing to the somewhat curved and twisted shape of 

 the parasite and the curling of the flagellum, in the stained 

 preparations, it was difficult to make exact measurements ; 

 but the average width, according to whether the membrane 

 was visible or not, varied from i to 2 ft, and the length 

 of the body from 20 to 30 ft. The flagellum was about 

 the same length as the body. 



From these observations (especially the discovery of the 

 undulating longitudinal membrane) the author recognised 

 a very close resemblance to Mitrophanow's descriptions, 

 and concluded that, if we followed the classification 

 adopted by Mitrophanow, the genus Hcsmatomonas must 



FIG. 133. A MONAD IN RAT'S BLOOD, x 3000. 



The organism is represented at partial rest, with its posterior filament im 

 pinging on a corpuscle, and showing the undulating longitudinal membrane, 

 the long flagellum, and the refractive spherules in the granular protoplasm. 



not be restricted to organisms in fish-blood. It must be 

 expanded to include this parasite of mammalian blood, 

 which should in that case be named Hcsmatomonas Evansi, 

 rather than Spiroch&td Evansi, as proposed by Steel. 



In the course of this investigation the author was led 

 to examine the blood of rats obtainable in this country. 

 Organisms were discovered in the blood of about 25 

 per cent, of common brown rats ; and, after examining 

 them with various objectives, from a \ dry to a ^ oil- 

 immersion of Powell and Lealand, the following con- 

 clusions were arrived at : That they are polymorphic, 

 presenting for the most part slightly tapering bodies 



