SECRETION PROCESSES. 453 



the stomach secreted a gastric juice containing pepsin, but no free hydro- 

 chloric acid. On the administration of soluble chlorides, a gastric juice 

 containing hydrochloric acid was immediately secreted. The conditions 

 are not so simple, because in the first case not only does the amount of 

 hydrochloric acid diminish but, as shown by WOHLGEMUTH, the quantity 

 of juice diminishes greatly, and on the introduction of NaCl the quantity 

 of juice secreted increases. According to PUGLIESE 1 the gastric juice 

 in starvation, after a certain time, has a neutral reaction, and the intro- 

 duction of Nad does not now change its properties. In the secretion of 

 free acid it is assumed by PUGLIESE that the gland cells, which decom- 

 pose the chloride, have sufficient amounts of protein at their disposal. 

 On the introduction of alkali iodides or bromides, KULZ, NENCKI and 

 ScHOUMow-SiMANOwsKi 2 have shown that the hydrochloric acid of the 

 gastric juice is replaced by HBr, and to a less extent by HI. According 

 to KOEPPE the seat of formation of hydrochloric acid is not the blood 

 or the glands, but the interior of the stomach in the immediate neigh- 

 borhood of the wall. The hydrochloric acid is assumed to be produced 

 from the chlorides of the food, as the semipermeable wall is not permeable 

 for the Cl ions, but is for the Na ions and for the H ions. As the Na ions 

 leave the stomach contents, an equivalent quantity of H ions wander 

 from the blood through the stomach wall into the interior of the stomach 

 and combine with the Cl ions. This theory is difficult to reconcile with 

 the fact that in dogs with sham feeding the empty stomach secretes 

 abundant juice. Other objections have also been raised against this 

 by BENRATH and SACHS. The secretion of free hydrochloric acid from 

 the alkaline blood has been explained in other ways (MALY, BUNGE, L,. 

 SCHWARZ), but as yet no satisfactory theory has been suggested. 3 



In regard to the secretion of pepsin we must recall that this last 

 is not already produced, but is formed from a preliminary step, a pep- 

 sinogen or propepsin. LANGLEY 4 has positively shown the existence 

 of such a substance in the mucous coat. This substance, propepsin, shows 

 a comparatively strong resistance to dilute alkalies (a soda solution of 

 5 p. m.), which easily destroy pepsin (LANGLEY). Pepsin, on the other 

 hand, withstands better than propepsin the action of carbon dioxide r 

 which quickly destroys the latter. The occurrence of a rennin zymogen 



1 Wohlgemuth, Arbeiten aus d. pathol. Institute, Berlin, 1906; Pugliese, Maly's 

 Jahresb., 3ti ; 394. 



2 Kiilz, Zeitschr. f. Biologic, 23; Nencki and Schoumow, Arch, des sciences biol. 

 de St. Petersbourg, 3. 



3 Koeppe, Pfliiger's Arch., 62; Benrath and Sachs, ibid., 109; Maly, see v. Bunge's 

 Lehrbuch der physiol. u. pathol. Chem., 4. Aufl., 1898; Schwarz, Hofmeister's Bei- 

 trage, 5. 



4 Schiff, Lemons sur la physiol. de la digestion, 1867, 2; Langley and Edkins, 

 Journ. of Physiol., 7. 



