44 SOME MINUTE ANIMAL PARASITES 



known to be infested by the tsetse, Glossina morsitans, 

 dreaded by native and trader alike. Examination of 

 the blood of the infected animals showed the presence 

 of numerous trypanosomes, and the parasite was 

 named Trypanosoma brucei in 1898 by Drs. Bradford 

 and Plimmer, in honour of its discoverer. 



The structure of T. brucei and several other 

 mammalian trypanosomes resembles that of T. gam- 

 biense in its essentials. The flagellum is perhaps a 

 little longer, and the membrane sometimes rather 

 more wavy than that of the human trypanosomes in 

 some cases, but the life-history of the Protozoon 

 follows practically the same course as that in man. 

 Again, the difficulty of successful treatment lies in 

 the administration of some drug which can not only 

 produce degeneration of the motile trypanosomes in 

 the blood of the host, but which can destroy the 

 latent forms lying dormant in the backwaters of the 

 blood-stream. The drugs previously mentioned in 

 connexion with human trypanosomiasis have been 

 used for horses and cattle, and with much the same 

 results. The use of arsenic in some of these cattle 

 diseases was 'advocated in the time of that great 

 African traveller, David Livingstone. 



Again, an additional trouble is provided by the 

 fact that there are certain wild animals antelopes, 

 gnus, etc. that are themselves immune to the 

 effects of T. brucei, but which harbour the trypano- 

 somes within their blood, and thus serve as living 

 reservoirs of disease. Further, the big game are 

 favourite feeding-grounds for G. morsitans. These 

 flies gorge themselves with blood and then leave 



