CHAPTER XI

NATURAL IMMUNITY AGAINST TOXINS 325 Examples of natural immunity against toxins.—Immunity of spiders and scorpions against tetanus toxin.—Immunity of the scorpion against its own poison.—Antivenomous property of the blood of the scorpion.—Immunity against tetanus toxin in the larvae of _Oryctes_ and in the cricket.—Immunity and susceptibility of frogs against this toxin.—Natural immunity of reptiles against tetanus toxin.—Antitetanic property of the blood of alligators.—Immunity of snakes against snake venom.—Immunity of the fowl against tetanus toxin.—Immunity of the hedgehog against poisons and venoms.—Immunity of the rat against diphtheria toxin.