Annual Address by the President. 
21 
reason it is well to pass on to the consideration of the next phase 
of the subject: 
IMMUNITY. 
The problem of immunity is so closely entwined with that of 
protective inoculation it will be easier to discuss the two conjointly. 
In its broadest sense, immunity represents that state of the living 
organism (animal or vegetable) which enables it to resist the toxic 
action of substances, whether such substances be introduced from 
an external source or are developed within the organism. Specific 
immunity is a state of immunity against a specific substance. This 
may be natural , as when the organism is normally non-susceptible ; 
or it may be artificial (acquired), as in the case of protection 
against disease developed by a previous attack of the disease (as 
in smallpox), or by some other artificial means (vaccination, for 
instance) . 
Vexed as the problem is, much enlightenment is to be gained 
from an investigation of artificial immunity. Recalling the 
researches of Jenner, and the quotation from Ehrlich relative to 
the work of Pasteur, at that time it appeared as though artificial 
immunity was brought about by specific micro-organisms. Opposed 
to this view the investigations of Toussaint, Chauveau, Salmon and 
Smith, Roux, C. Frankel, and others, brought forward evidence 
to show that artificial immunity could be induced by the “meta- 
bolic products” freed from bacteria — accustoming the organism to 
the specific poison seemed all sufficient. Later it was shown by 
Hueppe, G-amaleia, and Buchner that the specific toxins found in 
the culture fluid outside the bacterial cells were not identical with 
the protective substances found in the germs and their metabolic 
product^. 
At this point Hueppe 31 says : It has been “established that : 1, 
Undergoing the disease; 2, Inoculation with attenuated germs; 3, 
Inoculation with disease germs which have become wholly impo- 
tent ; 4, Inoculation with saprophytes ; and 5, Inoculation with the 
metabolic products of the parasite, can all confer immunity ; while, 
6, Inoculation with the specific poisons effects no immunization.” 
Then followed the experimental proof that completely attenuated 
bacteria can no longer produce the specific poison. This effectually 
separates the protective substance and the poison. 
The next important advance was the discovery of substances in 
the blood serum of animals immunized against diphtheria and 
tetanus that were able to specifically protect other animals against 
the toxines of these diseases. This discovery was made by Behring, 
