Page:Defensive Ferments of the Animal Organism (3rd edition).djvu/95

 the harmonious proteins of the plasma are not attacked by the ferments which circulate in the blood.

Finally, the question may be raised, why the decomposition of parenterally introduced proteins and peptones cannot be followed up directly, by observations on the rotating power of the plasma, without the addition of proteins or peptones. If the appearance of proteo- and peptolytic ferments in the plasma has the object of undertaking the decomposition of the substrates introduced into it, then we ought to be able to follow up the digestion—the decomposition—in the plasma itself. As a matter of fact it has been found possible to demonstrate, by means of intravenous introduction of large quantities of proteins and peptones, after the animals have been prepared by previous injections, that, when the blood is withdrawn immediately, not only has an alteration taken place in the original rotation of the plasma, to which nothing has been added, but also that peptones may be found in the outer fluid in the dialysation test. That this demonstration does not generally succeed—i.e., that the decomposition of the substances that are out of harmony with the body cannot be followed up by means of observations on the plasma alone, without the addition of substrates—depends primarily upon the fact, that the injected substances suddenly become