CHAPTER XI [341] 



NATURAL IMMUNITY AGAINST TOXINS 



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. 



As in this book we are dealing specially with the immunity against 

 infective diseases, the question of the resistance of the animal to 

 poisons interests us only in so far as it is related to immunity against 

 micro-organisms. Consequently the reader must not expect a treatise 

 on intoxications properly so called nor one on immunity against all 

 kinds of poisons. To perform such a task we should have to far 

 overstep the bounds of the subject that we have chosen and enter 

 upon an examination of questions which are beyond our sphere. Our 

 chief aim is to present to the reader a summary of our present 

 knowledge on immunity against microbial toxins and to establish 

 the relations between this kind of immunity and immunity against 

 infective micro-organisms. In order to do this, however, we shall 

 have now and again to go beyond the limits of our programme and 

 discuss certain problems bearing on the resistance of the animal 

 organism against poisons not of microbial origin. 



The immunity against toxins, like that against the micro-organisms 

 themselves, may be either natural or acquired. As many poisons 

 have been known from time immemorial, we are able to collect 

 numerous observations on the resistance of the animal organism to 

 such substances made when there was no idea of immunity against 

 infective diseases. The etiology of intoxications is often much more 

 evident and simple than is that of infections ; this is one of the [342] 



