Annual Address by the President. 
23 
protective value of venom and “antivenene” when administered 
by the stomach has already been mentioned. 
By this time the use of diphtheria antitoxin as a therapeutic 
agent in the treatment of diphtheria had become firmly estab- 
lished. The variation in the results obtained caused Ehrlich to 
search for a quantitative relation between the toxin of diphtheria 
and the antitoxin of diphtheritic serum. The result of Ehrlich’s 
investigation is to be found in the Croonian lecture delivered by 
him before the Royal Society, London, March 22, 1900. “By 
means of test-tube experiments with suspended animal tissues’* 
he brought out some very interesting facts. “The relations were 
simplest" in the case of red blood corpuscles. On them, outside the 
body, the action of many blood poisons, and of their antitoxines, can 
be most accurately studied, e. g., the action of ricin, eelserum, 
snake-poison, tetanus toxine, etc. * * * By means of these 
test-tube experiments, particularly in the case of ricin, I was able, 
in the first place, to determine that they yielded an exact quanti- 
tative representation of the course of the processes in the living- 
body. * * * It was shown that the action of toxine and anti- 
toxine took place quantitatively as in the animal body. * * * 
It was proved in the case of certain toxines — notably tetanus toxine 
• — that the action of antitoxines is accentuated or diminished under 
the influence of the same factors which bring about similar mod- 
ifications in chemical processes — warmth accelerates, cold retards 
the reaction, and this proceeds more rapidly in concentrated than 
in dilute solutions. * * * The knowledge thus gained led 
easily to the inference that to render toxine innocuous by means 
of antitoxine was a purely chemical process, in which biological 
processes had no share.” 35 
The distribution of the toxins and the antitoxins in the system 
is a matter of prime importance, yet not more than a beginning has 
been made looking toward their localization. That they do pos- 
sess a selective action has been established by Stokvis, Donitz, 
Pfeiffer, Marx, Wasserman and Roux, and these facts throw a 
great deal of light upon the phenomena of incubation, time reac- 
tions, antitoxic action, protective action, serum therapy, etc. 
The phenomena of agglutination and lysogenic action, the recent 
work of Buchner in Germany and Bordet in France on haemolysis, 
and some experimental work on ionic reactions done in my own 
laboratory deserve consideration here; but time presses for a sum- 
mation, and they must be passed without further comment to a 
future occasion. 
From accumulated facts, acquired immunity is separable into 
