TOXIN AND ANTITOXIN 



117 



Lo + -25 antitox. unit = 50 valencies = 50 lethal 

 Lo -f- antitox. unit = valency = 50 lethal 



The following spectrum, the third in Madsen's article, represents 

 the same toxin described in the preceding spectrum but at a later 

 period, at which considerable further deterioration had taken place. 

 The L dose now contained but 30 M L D or, in other words, the 

 amount of toxin contained in the L dose was sufficient to kill 30 

 guinea pigs only. 



PKOTOTOXOID 



ao 90100,10 



AFTER MADSEN, Ibid,., p. 579. 



Madsen's description of the method in which this spectrum is 

 constructed is the following : 



LO + f o& of an antitoxin unit kills guinea pig 

 LO + mi of an antitoxin unit kills guinea pig 



The amount of toxon has remained the same in spite of deteriora- 

 tion. As less and less antitoxin is added, between the values of -J$ 

 and ^$J of an antitoxin unit, there are now liberated only 5 fatal 

 doses of the toxin. It is in this zone that deterioration has taken 

 place, since, in the preceding spectrum, the difference between the 

 addition of %$-% and -J-J^ of an antitoxin unit represented 25 fatal 

 doses for guinea pigs. When in this last spectrum the amount of 

 antitoxin is gradually reduced from 100 valencies to 50 valencies 25 

 fatal doses are liberated, a quantity corresponding to the similar 

 zone in the preceding spectrum. Thus in this particular zone of the 

 spectrum no change has taken place. The same is true of the pro- 

 toxoid zone. 



It is unnecessary to cite a larger number of such measurements 

 in this place, since the ones given sufficiently illustrate the methods 



