In any event, it is very evident that the proteoses and peptones formed in the alimentary tract by pepsin-proteolysis must undergo some transformation, before reaching the blood-current, by which their peculiar physiological properties are modified. This modification may be associated with a conversion into the serum-albumin, or globulin of the blood. However this may be, the fact remains that these proteoses formed so abundantly during digestion can be absorbed and serve as nutriment for the animal body, but between their formation as a result of proteolysis and their passage into the blood they are exposed to some agency, or agencies, doubtless in the very act of absorption, by which a further transformation is accomplished. With this point we shall be able to deal more in detail in the next lecture. LECTURE III. PROTEOLYSIS BY TRYPSIN--ABSORPTION OF THE MAIN PRODUCTS OF PROTEOLYSIS. PROTEOLYSIS BY TRYPSIN. In pancreatic digestion, proteids are exposed to the action of an enzyme of much greater power than pepsin, one endowed with a far greater range of activity, and consequently proteolysis as it occurs in the small intestine becomes a broader and more complicated process. As you well know, the ferment trypsin manifests its power not only in a more rapid transformation of insoluble proteids into soluble and diffusible products, but there is a diversity in the character of the many products formed which testifies to the profound alterations this ferment is capable of producing. The primary and secondary products of pepsin-proteolysis, as well as unaltered proteids, are alike subject to these changes, and bodies of the simplest constitution may result in both cases from the series of hydrolytic changes set in motion by this proteolytic enzyme. The power of the ferment as a contact agent is astonishing, for in the case of trypsin no accessory body is necessary to bring out its latent power. Water, proteid, and the enzyme at the body-temperature are all that is necessary to call forth prompt and energetic hydrolytic action.