DIGESTION IN THE STOMACH. 457 



is neutralized the contractions of the sphincter cease and the passage 

 of new portions of the chyme occur. If the flow of bile and pancreatic 

 juice is prevented and the neutralization of the acid contents of the 

 stomach in the intestine is retarded, then the stomach does not eject 

 its contents so often. The duration of gastric digestion varies accord- 

 ing to conditions, and in consequence the reports of observers are 

 widely divergent. BEAUMONT l found in his extensive observations 

 on the Canadian hunter St. MARTIN that the stomach, as a rule, is 

 emptied IJ-oJ hours after a meal, depending upon the character of the 

 food. 



The time in which different foods leave the stomach also depends 

 upon their digestibility. Respecting the unequal digestibility in the 

 stomach we must differentiate between the rapidity with which the food- 

 stuffs are chemically transformed and that with which they leave the 

 stomach and pass into the intestine. This distinction is especially impor- 

 tant, and it is evident that the main factors governing speed of digestion 

 and the time required before the food leaves the stomach are the kind 

 of food and the fineness of its subdivision, and its action upon the 

 gastric secretion, upon the pyloric reflexes, etc. 



The observations of BOLDYREFF 2 on the action of fats are con- 

 clusive concerning the manner in which the properties of the food act 

 upon the gastric secretion and upon the digestion in the stomach as a 

 whole. Irrespective of the reducing action of the fats upon the extent 

 and digestive power of the gastric juice BOLDYREFF found after food 

 very rich in fat that the bile, pancreatic juice and intestinal juice migrate 

 from the intestine into the stomach so that the digestion in the stomach 

 in these cases is essentially brought about by the pancreatic juice. 



We have numerous investigations on the rapidity with which the 

 food is digested in the stomach of dogs, but we must especially mention 

 the researches of E. ZuNZ, 3 LONDON 4 and his co-workers. LONDON, 

 POLOWZOWA and SAGELMANN 5 have observed that all the foodstuffs 

 do not leave the stomach with the same rapidity, indeed, by feeding 

 with bread (POLOWZOWA) the carbohydrates leave more quickly than the 

 protein, and with a mixture of gliadin and beef-fat (SAGELMANN) the 

 protein left the stomach more quickly than the fat. According to these 



1 The Physiology of Digestion, 1833. 



* Pfliiger's Arch., 121. See also Abderhalden and Medigreceanu, Zeitschr. f. physiol. 

 Chem., 57. 



3 E. Zunz, Hofmeister's Beitrage, 3; Annal de la soc. roy. des sceinc. med. Bruxelles, 

 12, 13- and Memoires publ. par 1'Acad. roy. Belg., 1906, 1907, and 1908. 



4 The numerous works of London and co-workers will be found in Zeitschr. f. 

 physiol. Chem., 45-53, 55-57. 



5 London with Polowzowa, Zeitschr. 4. physiol. Chem., 49, with Sagelmann, ibid., 52. 



