Further, as already stated, absorption of proteid food-stuffs, or their products, from the alimentary tract, is, under ordinary circumstances at least, limited to the intestine; from the stomach there is comparatively little absorbed, and if necessary we might advance this fact as an important argument against the theory of general absorption of proteids in the form of acid-albumin. Even such indifferent fluids as water, or physiological salt solution, are absorbed with extreme slowness from the stomach;[206] this organ showing very little ability to take up water even when the blood-vessels are dilated, as after the ingestion of food. [206] J. S. Edkins: The Absorption of Water in the Alimentary Canal. Journal of Physiol., vol. 13, p. 445. This brings us to a very important point in connection with the utilization by the system of the ordinary products of proteolysis. The latter, as we have seen, are mainly proteoses and peptones, and yet all the evidence points clearly to the fact that these substances are never present, at least in any quantity, in the blood or lymph, even when digestive proteolysis is at its height. Further, the very nature of the proteoses and peptones, their marked physiological action when they are introduced directly into the circulating blood, their rapid excretion, either as proteoses or peptones, by the kidneys when so introduced,[207] all indicate that they are foreign substances, totally out of their natural environment when introduced into the blood-current. And yet we very well know that proteoses especially are possessed of high nutritive qualities; they are abundantly able to support animal life. Thus, Politzer[208] found by feeding experiments with heteroalbumose, dysalbumose, and protoalbumose, that these bodies taken into the stomach have the same nutritive value as meat. Various feeding experiments with proteoses from different sources, carried out in my laboratory on young dogs, have shown conclusively that for short periods of time, at least, these hydrolytic cleavage products are fully as capable of sustaining the nitrogenous equilibrium of the body as the proteids from which they are derived. In fact, the results obtained favor the view that the proteoses, weight for weight, possess a higher nutritive value than fresh beef.[209] It may be questionable, however, whether such a result would follow in experiments conducted over longer periods of time, but of this we may be certain, that the proteoses formed in the alimentary tract can be absorbed and utilized by the system without their exerting any toxic action whatever. [207] Franz Hofmeister: Ueber das Schicksal des Peptons im Blute, Zeitschr. f. physiol. Chem., Band 5, p. 125. [208] Ueber den Nährwerth einiger Verdauungsproducte des Eiweisses, Pflüger’s Archiv f. Physiol., Band 37, p. 301. [209] Compare Hildebrandt, Zur Frage nach dem Nährwerth der Albumosen, Zeitschr. f. physiol. Chem., Band 18, p. 120.