SAFEGUARDS OF THE BODY 
137 
ANTITOXIN. 
This curious something so potent and so beneficent 
was called antitoxin, because it acts by neutralizing or 
abolishing the harmful effects of the toxin—that is, 
the poison of the diphtheria germ. 
No chemist has ever been able to separate antitoxin 
from the blood serum; no man knows its composition; 
but there it is, the heart, it seems, of the mystery of 
immunity. 
One might think that we had found here some re¬ 
markable cure-all in this antitoxin, and that it would 
prevent or cure other infectious diseases. But this 
is not the case. It has no more effect in the preven¬ 
tion or cure of other diseases, such as pneumonia, 
typhoid fever, etc., than so much water. In other 
words, its action is specific. 
The seeker of light in fields relating to medicine 
is rarely free from the consciousness of urgency in the 
solution of his problem. So the moment he found 
that lie could protect the lower animals against the 
ravages of diphtheria which he had artificially induced, 
he turned at once to the possibility of human protec¬ 
tion and cure. And the situation was indeed urgent. 
No disease was more dreaded than diphtheria, espe¬ 
cially in children; the suffering of the victims was 
pitiful, the mortality great. 
The first experiments were made on small animals, 
but if the serum were to be used in children larger 
quantities would be required, so sheep and goats were 
