22 TOXINES AND ANTITOXINES. 



Direct introduction into the circulatory system (intravenous) 

 is still more effective than intraperitoneal, intercerebral, or sub- 

 dural inoculation, as has been used in the case of tetanus and 

 gonococci poisons, or yet HOMEN'S method of injection into the 

 nerves, which is sometimes employed. 



Intercerebral injection is of special importance in cases where 

 either the poison when distributed throughout the body is 

 seized by the receptors or other less susceptible organs (tetanus 

 in the rabbit), or where the receptors in the brain are not very 

 numerous, so that only concentrated toxine can effect any serious 

 injury (tetanus in the hen). 



As regards the activity of toxines, there are two factors of 

 fundamental importance their specific character, and the time 

 of incubation. 



The specific character is one of the most prominent character- 

 istics of true toxines. Although more or less thorough resistance 

 to the action of crystalloid poisons is known, cantharidine, for 

 instance, being relatively innocuous to the hedgehog and atropine 

 to pigeons ; yet in these cases there is only a weakening of the 

 activity of the poison, and not an absolute resistance. Certain 

 bacterial poisons, however, are completely harmless to refractory 

 animals, while they act with the greatest energy upon susceptible 

 animals. 



But the most important point in this connection is that, in the 

 case of refractory animals, the toxine is by no means destroyed, 

 but that it circulates unchanged in their blood as a completely 

 inert substance. 



Thus arises the paradoxical phenomenon which we have de- 

 scribed at some length above, that it is possible to kill a mouse 

 with tetanus, by means of the blood of an apparently healthy 

 hen which has previously been inoculated with large doses of 

 tetanus poison. When the toxine cannot find corresponding 

 receptors it is unable to make its attack. The toxophore group 

 remains inactive, with the result that the toxine is a completely 

 inert substance which the body regards as of so little importance 

 that it does not even make speedy attempts to destroy it. This 

 phenomenon, too, can readily be explained by the side-chain 

 theory. According to EHRLICH, all nutritive substances, so far 

 as they are not merely chemically changed by the secretions and 

 their enzymes, enter into combination as haptines, and are thus 

 brought within the power of the destructive and assimilative 

 forces of the protoplasm. But, since the toxine does not enter 

 into such combination, it also is not destroyed not even treated 

 in the same way as nutritive substances. 



