26 



IMMUNE SERA 



that this action is due to a separate poison excreted 

 by the diphtheria bacillus which he calls a toxon. 



If we continue with the above poison we shall 

 obtain these values: 



# cc poison + ^ = Toxin action (i fatal dose). 



# cc poison + sVu =30 fatal doses. 



x cc poison + sVk = 90 fatal doses, etc. 



That is to say, if we add only $fo units antitoxin, 

 i.e. sitf unit less than in the JH mixture, we find 

 that one fatal dose is set free. This relation would 

 exist right to the end. The fact that in this experi- 

 ment the toxins are liberated after the toxons, 

 shows that the toxons have less affinity for the anti- 

 toxin than have the toxins. 



As a matter of fact, however, conditions are prob- 

 ably never as simple as this. In the process of 

 toxin formation a double action is always going 

 on that of toxin and toxon production, and that 

 of their decomposition. As was pointed out on 

 a previous page the poisons quickly change into 

 non-poisonous toxoids, and these substances are 

 still able to bind antitoxin. 



This is shown in the following " spectrum." 



Protoxoid 



10 20 30 40 50 60 



1GO 



FIG. 3. 



Toxon 



150 160 



