According to our observations, there is not the slightest doubt that the animal organism is not left without means of defence against disharmonious substances. If such products make their way into the body, the latter sends out defensive ferments that are directed against special kinds of substrates. Not only do they effect the destruction of the specific character of the parenterally introduced substance by means of an extensive decomposition, but they render possible the utilization of the products of the decomposition in the general metabolism. The reaction we have demonstrated enables us at any time to decide whether a certain substance is in harmony with the body or not. We have already emphasized the fact that we must distinguish not only substances that are in, or out of, harmony with the body, but also those which are in, or out of, harmony with the blood or its plasma, or again with the cells. We have already described how the intestine, with its ferments and those of its accessory glands, decomposes all disharmonious substances until an indifferent mixture of only the simplest units is left; and how then the cells of the gut-walls, and of the liver, carefully test the absorbed products for the absence, or transformation, of all substances that are out of harmony with the body and blood. Moreover, all the cells of the body take care that nothing shall pass from them into the circulation which has not attained a certain
