Page:Defensive Ferments of the Animal Organism (3rd edition).djvu/83

 into the organism, so as artificially to avoid the disintegrating action of the ferments of the intestines. These substances are injected either subcutaneously, or into the abdominal cavity, or else intravenously. After a certain lapse of time blood is extracted, and its serum, or plasma, is treated exactly in the same way as we have described above.

The first experiments were made with dogs and rabbits. White of egg, or horse blood-serum, was introduced parenterally into these animals, that is to say, avoiding the intestinal canal; tests were then made to see whether the plasma of the animals under experiment either decomposed certain polypeptides, or whether it decomposed them quicker than the plasma of the same animal did before the injection of the disharmonious substance. The very first experiments gave a positive result. It was found that the contents of the blood increased in peptolytic ferments. In a further experiment the substance used for the injections was silk-peptone. It was found that the serum of normal rabbits did not reduce this peptone at all, the angle of rotation of the mixture of plasma + peptone remaining constant. But if silk-peptone be injected into an animal, and the serum of the latter be then brought into contact with this peptone, then, if we take a rapid reading of the rotation in a polariscope, we find that the initial rotation alters in the course of time.