462 DIGESTION. 



after tying the smaller blood-vessels of the stomach of dogs the cor- 

 responding part of the mucous membrane was digested, efforts have been 

 made to find the cause in the neutralization of the acid of the gastric 

 juice by the alkali of the blood. That the reason for the non-digestion 

 during life is to be sought for in the normal circulation of the blood can- 

 not be contradicted; but the reason is not to be found in the neutral- 

 ization of the acid. The investigations of FERMI and OTTE l show that 

 the blood circulation acts in an indirect manner by the normal nourish- 

 ment of the cell protoplasm, and this is the reason why the digestive 

 fluids, the gastric juice as well as the pancreatic juice, act differently 

 upon the living protoplasm as compared with the dead. We know 

 nothing about this resistance of the living protoplasm. Some claim that 

 it is closely connected with the secretion of the antipepsins discovered 

 by DANILEWSKY, HANSEL, and WEINLAND, but this is hard to understand. 

 Undoubtedly bodies occur in the gastric mucosa which can inhibit the 

 action of pepsin, but whether these bodies are of an enzymotic nature 

 or not is undecided. WEINLAND'S antipepsin is related to the enzymes 

 because it is thermolabile, while the antipepsin of DANILEWSKY, HAN- 

 SEL, and O. SCHWARZ 2 is resistant toward heat and can hardly be con- 

 sidered as an enzymotic body. This is true for at least the thermo- 

 8tabile antipepsin of SCHWARZ, which does not give the biuret reaction. 

 Without mentioning the still unknown nature of these bodies, the natural 

 gastric juice, as well as an acid infusion of the mucosa, has such a strong 

 digestive action that the retarding action of the antipepsin can only be 

 shown under special conditions, and it is therefore difficult to conceive 

 how the antipepsin could have a protective action in life. 



Under pathological conditions irregularities in the secretion may 

 occur. The quantity of enzymes may be diminished and both enzymes 

 or, as found in certain cases, one (the chymosin), may be absent. 

 The hydrochloric acid may also be absent or may exist in very small 

 amounts. A pathological high degree of acidity of the pure juice is not 

 very probable, while on the contrary a hypersecretion of gastric juice 

 in different forms does occur. 



In testing the gastric juice or the filtered stomach contents, diluted 

 with digestive hydrochloric acid, for pepsin we make use of the pepsin 

 tests given on pages 445, 446. In testing for rennin the liquid must be 

 first carefully neutralized and 1-2 cc. of this liquid added to 10 cc. 

 milk. In the presence of appreciable quantities of rennin, the milk 



1 Pavy, Phil. Transactions, 153, part I, and Guy's Hospital Reports, 13; Otte, 

 Travaux du laboratoire de 1'Institut de Physiol. de Liege, 5, 1896, which also contains 

 the literature. 



2 See Hansel, Biochem. Centralbl., 1, p. 404, and 2, p. 326; Weinland, Zeitschr. f. 

 Biologic, 44; Schwartz, Hofmeister's Beitrage, 6. 



