Annual Address by the President. 
25 
3. The Theory of Acclimatisation or Habituation has limited 
application, and like the theory of Adaptation, takes too little cog- 
nizance of details. 
4. Metschnitcoff’ s Theory of Phagocytosis falls before the facts 
of passive immunity; and 
5. The Humoral Theory only presents another phase of its own 
evolution. 
6. Buchner's hypothesis, which explains immunity as being due 
to the reactive changes in the integral cells of the body resulting 
from the action of chemical products absorbed from the seat of 
vaccination or inoculation, is strongly supported by experimental 
evidence; and 
7. Ehrlich's 37 side-chain (Seitenkette) theory presents an ex- 
ceedingly ingenious and interesting explanation of the phenomena 
of immunity adduced by experiments in vitro and in vivo.. 
By elimination the problem may be somewhat simplified. The 
facts themselves may be roughly divided into two groups: 1. Bio- 
logical; and 2, Chemical; and the explanations will then be either 
biological or chemical. In the ultimate analysis: the Biological 
explanation will rapidly pass from the body as a whole to its 
respective organs and their respective cells, to the nucleated cells, 
and finally to the biogen of the nucleus; while the Chemical 
explanation will describe the cycle that begins with the minutest 
atomic reaction, passes onward through more and more complex 
intra- and interm olecular synthetic and analytic changes so long 
as chemical equilibrium is disturbed ; but eventually finds its begin- 
ning and its end — cause and effect — in energy potential, energy 
kinetic, liberating impulse. 
That the problem of immunity will be solved is only a question 
of time. The active research now in progress is rapidly dissipat- 
ing the unknown; and when the chemical structure of the various 
animal proteids becomes a known quantity their interaction will be 
readily seen and the solution of the problem will be an accom- 
plished fact. 
The problem is a biochemical one, and biochemists will solve - it. 
Many if not all the phenomena of fermentation, infection and 
immunity are explainable in terms of modern chemistry, and since 
modern chemistry is firmly founded on the doctrine of energy we 
have to consider merely the terms: energy potential, energy 
KINETIC and LIBERATING IMPULSE. 
I am conscious of having failed to bring before you a large mass 
of newly accumulated interesting facts which should be considered 
in this connection; but the largeness of the subject, together with 
