Natural immunity against toxins 327 



mdard we may inject into them, with impunity, more than 6000 

 Eimes as much toxin as into mice, without setting up a single morbid 

 symptom. Scorpions, like the 3Iygale, live well in the incubator at 

 36° C, where they are kept whilst submitted to the action of the 

 tetanus poison. Here again we have to do with a case of histogcnic 

 immunity. The fluids of the scorpion exert no antitoxic action. 

 ^yhen blood from the normal scorpion is mixed with various doses of 

 tetanus toxin and injected into mice these animals contract tetanus 

 and die just as do the control animals. In certain exceptional cases 

 some slight retardation was observed, but the blood of the scorpion 

 is, in most cases, incapable of preventing tetanus in animals sus- 

 ceptible to this disease. 



Scorpions, injected with tetanus toxin, do not retain it in their 

 blood for long. A few days after the injection of the tetanus poison 

 such blood, when injected subcutaneously into mice, excites no trace 

 of tetanus. The preparation of extracts of the difierent organs of 

 scorpions treated with tetanus toxin demonstrates that the liver and 

 the liver only absorbs the poison. It is found there a few days after 

 the injection of the toxin and it remains there unaltered for some 

 considerable time. The exudation of the liver of scorpions, killed a 

 month or more after the introduction of the toxin into the general 

 cavity, injected into mice sets up a typical and fatal tetanus. 



The presence of the tetanus toxin in the organism of scorpions 

 does not give rise to the production of antitoxin. At any rate a 

 Avhole series of experiments on this point carried out by us never 

 gave a positive result. The scorpions resisted repeated doses of the 

 tetanus toxin and lived without any difficulty at 36° C, but their 

 blood was never at any period capable of preventing mice from 

 contracting fatal tetanus. Nevertheless the scorpion may possess 

 antitoxic power. 



Everyone has heard of the supposed suicide of the scorpion. We 

 are told that when this animal finds itself under conditions in which its 

 death is inevitable, it stings itself with the end of its tail and dies 

 from the efiect of its own poison. A simple method of reproducing [344] 

 this experiment is actually described : — Surround the scorpion with a 

 circle of fire. The animal rushes in all directions to find a way out, 

 and finding none, deliberately commits suicide. Bourne^ at Madras 

 carefully investigated this question in a large species of Indian 



1 Froc. Roy. Soc. London, 1887, Vol. xlii, p, 17. 



