1. Black snake toxin produces irreversible paralysis of the isolated toad gastro-cnemius-sciatic preparation.
2. The rate of paralysis is slowed by lowering the concentration of toxin.
3. The paralysis produced by the black snake toxin is due to neuromuscular block. Conduction in the nerve is unaffected and the muscle is only slightly affected.
4. The neuromuscular block produced by the toxin differs from that of curare in that tetanus is well maintained and that paralysis is unaffected by prostigmine or potassium.
5. The neuromuscular block produced by the toxin differs from that of curare in that the motor end-plates remain sensitive to acetylcholine.