1. It was found that the black-wildebeest was susceptible to A. marginale but no clinical symptoms were noticed.
2. Neither P. bigeminum nor Th. mutans could be transmitted to the black-wildebeest.
3. A. marginale neither lost its virulence not its characteristic morphology ·by passage through the black-wildebeest.
4. The fact that the black-wildebeest is susceptible to A. marginale but refractive to P. bigeminum and Th. mutans, indicates that this antelope can also be utilized for separating these three parasites which usually occur together in South Africa and thus obtaining pure infection of A. marginale.