192 CHEMICAL MECHANISMS OE SECRETION 



stomach does not secrete during inanition, but commences a few 

 minutes after a meal. The quantity of juice from a pancreatic 

 fistula during hunger amounts to only two or three c.c. per hour, 

 but some time after a meal increases to many times that amount. 



2. The quantity of juice secreted in the case of the same food 

 is directly proportional to the quantity of food taken. Thus 

 for raw meat, for 100 grm., 26 c.c. of gastric juice were secreted ; 

 for 200 grm., 40 c.c. of juice, and for 400 grm., 106 c.c. On a 

 mixed diet of meat (50 grm.), bread (50 grm.), and milk (300 c.c.) 

 42 c.c. of gastric juice were secreted, for double these quantities 

 83 *2 c.c. were secreted. 



3. The secretion is not all poured out rapidly at the beginning, 

 but is distributed throughout the period of digestion, and the 

 curve of quantity secreted and time varies for the different types 

 of food. Each food possesses a modifying effect both upon the 

 quantity and quality of the secretion. Also the presence of one 

 food has a modifying power upon the secretion called forth by 

 another, and on the whole course of digestion. 



Thus in the case of gastric secretion of a meal of flesh, bread, 

 or milk respectively. Each separate food corresponds to a definite 

 hourly rate of secretion, and calls forth a characteristic alteration 

 of the properties of the juice. Flesh and bread diet produces 

 a maximum rate during the first hour of digestion, while milk 

 gives the maximum rate during the second or third hour. Tested 

 as to maximum content in ferment during the period of digestion, 

 the greatest activity is found with flesh diet in the beginning ; 

 with bread in the second and third hours ; and with milk in the 

 last (or sixth) hour. Contrasting the digestive power of the juices 

 for proteid at corresponding periods of digestion in the case of 

 the three foods, the greatest power is found in the case of the flesh 

 diet, the bread comes second, and, in the earlier stages at least, 

 close to the meat, while that on the milk diet is much feebler in 

 proteolytic power. 



In the case of the pancreatic secretion, a similar adapta- 

 tion of the secretion to the nature of the food is seen, and 

 here the changes become more striking; because there is a 

 ferment for each class of food-stuff, and relative variations can 

 be contrasted. 



The following table of results by Walther, quoted by Pawlow, 

 gives the variation in secretion (quantity and ferments) of pan- 



