r example, a dissolving action on
red corpuscles, this action may be annulled by previously adding the
antitoxin to toxin; in such a case the intervention of the living tissues
is excluded. In view of the fact that antitoxin has a direct action on
toxin, we may say that theoretically this may take place in one of two
ways. It may produce a disintegration of the toxin molecule, or it may
combine with it to produce a body whose combining affinities are satisfied.
The latter view, first advocated by [v.03 p.0177] Ehrlich, harmonizes with
the facts established with regard to toxic action and the behaviour of
antitoxins, and may now be regarded as established. His view as to the dual
composition of the toxin molecule has already been mentioned, and it is
evident that if the haptophorous or combining group has its affinity
satisfied by union with antitoxin, the toxin will no longer combine with
living cells, and will thus be rendered harmless. One other important fact
in support of what has been stated is that a toxin may have its toxic
action diminished, and may still require the same amount of antitoxin as
previously for neutralization. This is readily intelligible on the
supposition that the toxophorous group is more labile than the
haptophorous. There is, however, still dispute with regard to the exact
nature of the union of toxin and antitoxin. Ehrlich's view is that the two
substances form a firm combination like a strong acid and a base. He found,
however, that if he took the largest amount of toxin which was just
neutralized by a given amount of antitoxin, much more than a single dose of
toxin had to be added before a single dose was left free. For example, if
100 doses of toxin were neutralized by a unit of antitoxin (_v. supra_) it
might be that 125 doses would need to be added to the same amount of
antitoxin before the mixture produced a fatal result when it was injected.
This result, which is usually known now as the "Ehrlich phenomenon," was
explained by him on the supposition that the "toxin" does not represent
molecules which are all the same, but contains molecules of different
degrees of combining affinity and of toxic action. Accordingly, the most
actively toxic molecules will be neutralized first, and those which are
left over, that is, uncombined with antitoxin, will have a weaker toxic
action. This view has been assailed by Thorvald Madsen and S. A. Arrhenius,
who hold that the union of toxin and antitoxin i