150 CONCERNING GLOsSINA MORSITANS. 



to be infective ; in North-Eastern Rhodesia of two species of antelope ; in the 

 C^ongo State of one. 



Conditions for inoculation e.vperiments. — Such experiments must be carried 

 out by a competent person and all precautions taken against infection through 

 natural channels. Montgomery and Kinghorn write : — " The ideal system 

 would be to establish temporaiy camps in various districts with a plentiful 

 stock of healthy animals carefully protected in fly-proof cages at hand, and 

 to inoculate such immediately on the death of the game, or to convey citrated 

 blood back with as little delay as possible. This would have to be carried out 

 in both clean (fly-free) and tsetse-infested districts ; and it is one of the first 

 problems in the etiology of trypanosomiasis that this should be undertaken. 

 In Northern Rhodesia, and elsewhere, considerable difficulties will be experi- 

 enced owang to the non-pathogenicity of certain endemic trypanosomes 

 towards the ordinary laboratory animals ; it w^ould appear almost imperative, 

 therefore, that sheep and goats should be employed." 



Choice of experimental animal. — The latter part of this quotation illustrates 

 one of the difficulties, that of finding a suitable susceptible animal. For the 

 Zululand trypanosome the dog w^as such an animal, as appears to have been 

 the case also in inoculation experiments by Brand in Northern Nigeria. In 

 North-Eastern Rhodesia on the other hand, inoculated dogs often failed to 

 show trypanosomes, even though they became ill and died. It was necessary 

 to use sheep and goats. 



Bouffard, wdio reported on a trypanosome disease in the Niger territory 

 known as Baleri (^Trypanosoma pec audi) ^ found the cat the most useful animal 

 for inoculation purposes. It sickened surely and rapidly, and was easily 

 handled. 



The choice of the experimental animal is most important. It should be a. 

 species which not only invariably becomes infected but shows also a good 

 blood invasion of parasites, so that the diagnosis can be readily made. For 

 reasons of expense both in purchase and maintenance, it should be of small 

 size. Sheep and goats do not conform well to these conditions. There are, 

 however, animal trypanosomiases, e. g. those due to Trypanosoma vivaA\ 

 Irypanosoma cazalboui, and to some extent to Tryjmnosoma nanum, which 

 cannot be transmitted to the small laboratory animals. 



Owing to " individual equation " in any susceptible species, it is well to 

 inoculate more than one animal in any given case. The inoculation should be 

 done in a uniform way, either beneath the skin or peritoneum, and a similar 

 dose employed. The dose should be diluted with saline solution, for, when 

 this precaution is omitted, infection sometimes fails. When possible, blood 

 from a suspect should be taken at intervals for testing, as it might be non- 

 virulent one day and virulent another. 



Inoculations to he made from the smaller mammals. — All inoculations recorded 

 np to now have been made from the larger animals. It is important that the 



