THE CONSTITUTION OF THE TOXINE AND ITS RELATION TO 
ANTITOXIN. 
Ehrlich’s discovery that the relation between toxine and antitoxin is 
not always the same led him to investigate the constitution of the 
diphtheria poison. 
It is believed that the diphtheria bacillus primarily secretes at least 
two poisons, the toxin and the toxone. 
The toxin is not stable and is readily reduced to toxoid. For the 
purposes of our work we must have a clear understanding of the toxin., 
the toxoid., and the toxone. 
The toxin is the onh^ poison produced b}" the diphtheria bacillus 
capable of causing acute death. The toxoids have little or no poi- 
sonous properties. The toxones produce the late manifestations of 
paralysis. 
The interesting point about all of these poisons is, the}^ have the 
power of combining chemically with the antitoxin. In other words, 
toxin., toxoid., and toxone., and finally ej)itoxonoid^ all have the same 
haptophore group, but different or modified toxophores. 
The poisonous toxins are subdivided into three groups depending 
upon the degree of their avidity for antitoxin, \\z., 2)rototoxm ^ deutro- 
toxin, and tritotoxin. Each of these toxin groups may in whole or in 
part be converted into toxoids., which are not poisonous but which 
have the same power of combining with the antitoxin as the toxin 
from which they derive their origin. These altered toxins are conse- 
quently known as prototoxoid, deutrotoxoid, and tritotoxoid, respec- 
tivel}\ The ]?rototoxin has a greater affinity for antitoxin than the 
deutrotoxin, and the deutrotoxin has a greater affinit}" for antitoxin 
than the tritotoxin. The same relation holds good for the three toxoids. 
As each diphtheria poison contains these substances in varying pro- 
portions it is at once evident that there can be no relation between the 
toxicity of the poison and its combining power with antitoxin. Take 
for example two poisons which require the same dose to kill, but in 
one the p)^'ototoxin and in the other the tritotoxin has become altered 
mto prototoxoid and tritotoxoid, respectively. It is then evident that 
in order to neutralize the same lethal dose in the first case it would 
require more serum than in the second, because in the first case a cer- 
tain proportion of the antitoxin would be used up b\^ combining with 
the prototoxoid, which is nonpoisonous, leaving a proportionately 
greater amount of uncombined toxin. On the other hand, a serum 
tested against ten or one hundred minimal lethal doses of these 
respective poisons would appear to have quite different immunizing 
values. 
( 25 ) 
