16 Sir D. Bruce and Capts. Hamerton and Bateman. [Sept. 18, 



set down for each trypanosome encountered in Africa, then some classifica- 

 tion of the African species might be attempted. But it is only for a few 

 species, such as Trypanosoma gambiense and Trypanosoma brucei, that we 

 have all these data. Take, for example, the case of Trypanosoma congolense 

 (Broden) and Trypanosoma dimorplion (Dutton and Todd) — most important 

 trypanosome diseases. Laveran thinks they are distinct on account of a 

 cross-inoculation experiment, but Broden himself, Bodhain, and Dutton and 

 Todd all seem to lean to their really being one and the same species. 

 With the data at our disposal at present it is impossible to come to a definite 

 decision. 



At the present time the classification of the pathogenic trypanosomes is in 

 & state of chaos, and we have no desire to add to the confusion. Neverthe- 

 less, we think it will be well to give a description of Dr. Edington's 

 trypanosome, as far as we have been able to study it, in view of the fact that 

 we are starting at once for Uganda to continue the investigation of sleeping 

 sickness. 



Morphology of Dr. Edington's Trypanosome. 



A. Living, unstained. 



Dr. Edington's trypanosome in the fresh condition, as seen in a drop of 

 blood from an infected guinea-pig or rat, appears short and stumpy in 

 •outline, about twice the diameter of the red blood corpuscles, among which 

 it slowly moves, with, as a rule, its rapidly- vibrating flagellum in front. The 

 posterior or non-fiagellar extremity appears blunt and rounded off abruptly, 

 while the anterior tapers off to a fine point. In the fresh preparation the 

 undulating membrane is not much in evidence, though sometimes it can be 

 seen thrown into waves. The contents of the cell are homogeneous, except 

 for a small refractile body at the posterior extremity, which is evidently the 

 micro-nucleus. 



B. Fixed and stained. 



Method of staining. — The method used for fixing and staining the 

 trypanosomes is usually as follows. The blood-film while still moist is 

 exposed to the vapour of a 4-per-cent. solution of osmic acid in distilled 

 water, to which a drop of glacial acetic acid has been added, for 45 seconds. 

 The cover-glass is then transferred to absolute alcohol for from five minutes 

 to half an hour. It is then passed through grades of alcohol from 80 per cent, 

 to 10 per cent, in distilled water. Twenty-five drops of Giemsa's stock 

 stain (Gnibler's) are now mixed with 25 c.c. of distilled water. The films 

 are placed in this, face downwards, for 8 to 12 hours, then washed in distilled 

 water, and rinsed quickly in solution of orange tannin (orange G. 1 per cent., 



