to the conclusion that they would do so, because it had been noticed that, after the introduction of disharmonious substances into the circulation, not only do ferments appear which reduce the particular compound inoculated, but the defensive ferments produced attack many other substances of the same order. There was no production of strictly specific ferments, but only of those which are limited in their action to a particular class of compounds. And when substances that were in harmony with the body, but not with the plasma, were chosen for these experiments, no ferments appeared that were strictly specific.
We tested the sera of tuberculous individuals, of sufferers from carcinoma, of persons with salpingitis, and others, for their behaviour towards placental tissue, but in not a single case did decomposition take place. To our great surprise it appeared, that the animal organism only sets free strictly specific ferments, when particular cells are themselves giving off substances which are not in harmony with the plasma.
How can we explain this different mode of behaviour, according to whether we introduce such disharmonious substances, or whether the organism itself supplies them? There are various possibilities to be considered. In the first place the cell may give off the substances in question only in minute quantities, a condition which we are unable to imitate. Our methods of interference are
