The involvement of collagenase in the necrosis induced by the bites of some spiders.

1. The midgut extracts of 13 Australian spider species produced cellular disruption in mouse skin in tissue culture conditions. 2. Microbial collagenase and the venoms of some of these species had similar effects. 3. Five venoms also caused severe dermonecrosis in living mice. 4. Pre-mixing the venoms with L-cysteine caused complete in vivo and partial in vitro inhibition of their effects. 5. It was concluded that collagenase is a major factor in the aetiology of necrotic arachnidism.