416 



On a Trypanosome in the African Elephant. 



Conclusions. 



In our present state of knowledge it seems impossible to name trypano- 

 somes from their form alone. We were, however, much surprised, a short 

 time ago, by Sir John McFadyean separating with ease Trypanosoma brucei 

 from Trypanosoma evansi. If this can be done for such closely related 

 species, surely it should be possible to do it for all. To assist to this end it 

 would be well if observers would adopt one method of fixing, staining, and 

 measuring. In the ' Third Report of the Wellcome Research Laboratories,' 

 Khartoum, facing p. 30, there is a coloured plate of trypanosomes, stated to 

 have a magnification of 1000. On measuring one of them it is found to have 

 a magnification of between 2000 and 3000. Then, again, many of the 

 trypanosomes depicted are dividing forms, which is misleading. 



The method of measuring must also make a difference. For example, in 

 Laveran and Mesnil's book the length of Trypanosoma brucei in the rat is 

 given as 26 to 27 microns, whereas by our method of measuring the average 

 length of 20 individuals is 22 - 8 microns : maximum 25, minimum 20. 



The trypanosome of the elephant has an average length of 18 - 5 microns : 

 maximum 21, minimum 15, a well-developed undulatory membrane and free 

 flagellum. The trypanosomes with free flagella are Trypanosoma brucei, 

 cazalboui, evansi, gambiense, pecaudi, and soicdanense. It probably is neither 

 Trypanosoma cazalboui nor pecaudi, on account of its well-developed 

 undulating membrane and uniform size. Under the circumstances it is 

 impossible to decide as to its identity with Trypanosoma brucei, gambiense, or 

 soudanense, but if a guess were hazarded then it would be Trypanosoma 

 soudanense. 



Until the nature of this species is better known we propose to name it 



Trypanosoma elephantis. 



