1. Weitz, B. G. F., Nature, 185, 788 (1960).
2. Weitz, B. G. F., J. Gen. Microbiol., 23, 589 (1960).
3. Miller, J. K., Immunology, 9, 521 (1965).
4. Njogu, A. R., Intern. Council for Trypanosomiasis Res. Publication 100, 75, Lagos (1966).
5. Rudzinska, M. A., and Vickerman, K., in Infectious Blood Diseases of Man and Animals (edit. by Weinman, D., and Ristic, M.), 1, 217 (Academic Press, New York, 1968).