active ferment, retains its initial angle of rotation; and it is only in very exceptional cases that dialysis shows the presence, in the outer fluid, of substances that give the biuret reaction. It is only after proteins or peptones are added to the plasma, that the activity of the ferments first manifests itself.
How can we explain a behaviour that is, a priori, so peculiar? There are already, before the addition of the proteins or peptones, large quantities of albumen in the plasma in the presence of an active ferment. We must always remember, in this connection, that the ferments are directed, in a more or less explicitly specific manner, against certain substrates. A slight alteration in structure and configuration suffices to remove a substrate from the influence of a given ferment. Just as the ferments themselves are first transformed into their active form by means of a special agent, so, without doubt, the substances in the blood and the cells which are presented to the ferments need special agents to bring them into a condition suitable for attack.
The substrates, too, are rendered active in a certain sense. The body defends its cells, and the substances contained in them, against disintegration by ferments by giving them a structure and configuration—it may be that their physical condition also plays a part—which are out of harmony with the ferments; and from this point of view we can understand why
