An endogenous antitoxin to the lethal venom of the funnel web spider, Atrax robustus, in rabbit sera

1. An endogenous antitoxin fraction was isolated from non-immune rabbit sera by affinity chromatography with robustoxin bound to the solid support. 2. Robustoxin is the sole lethal toxin in the venom of the male funnel web spider, Atrax robustus. 3. The fraction was found to contain IgG and IgM immunoglobulins. 4. This fraction prevented or reversed the lethal actions of the crude venom in newborn mice, in mouse phrenic nerve-hemidiaphragm preparations, and in anaesthetized monkeys. 5. The antitoxin fraction is of potential value in the therapy of human envenomation by A. robustus.