1. Grasso, A., and Poggi, P., Toxicon, 5, 1 (1967).
2. D'Ajello, V., Mauro, A., and Bettini, S., Toxicon, 6 (in the press).
3. D'Amour, F. E., Becker, F. E., and van Riper, W., Quart. Rev. Biol., 11, 123 (1936).
4. Sampayo, R. R. L., J. Pharmacol. Exp. Ther., 80, 309 (1944).
5. Cantore, G. P., Riv. Parass., 19, 297 (1958).