DIGESTION. 



79 



"bread-juice"; the next strongest is "flesh-juice," and then comes 

 "milk-juice." In other words, "bread-juice" contains four times as 

 much ferment as "milk-juice." Not alone the digestive power, but 

 likewise the total acidity, varies according to the nature of the diet. 

 Comparing equivalent weight, flesh requires the most and milk the 

 least gastric juice; but taking equivalents of nitrogen, bread needs 

 the most and flesh the least. The hourly intensity of gland work is 

 almost equal in the case of milk and flesh diets, but far less with 

 bread. The bread, however, exceeds all others in the time required 

 for its digestion, and the duration of the secretion is correspondingly 

 protracted. 



Meat. 



Bread. 



Milk. 



8 



<^ ^ 



" 

 II 



^ ,O 

 rO >-^ 



3 * 5 6 7 



l.J 34* 



Fig. 17. Hourly Variations of the Digestive Power of the Gastric 

 Juice in the Dog after a Meal of Meat, Bread, and Milk. (PAWLOW, 

 GLEY. ) 



Each separate kind of food corresponds to a definite hourly rate 

 of secretion, and calls forth a characteristic alteration of the proper- 

 ties of the juice. Thus, with flesh diet, the maximum of secretion 

 occurs during the first or second hour, and in both the quantity of 

 juice furnished is approximately the same. With bread diet we have 

 always a sharply indicated maximum in the first hour, and with milk 

 a similar one during the second or third hour. On the other hand, 

 the most active juice occurs with flesh in the first hour, with bread 

 in the second and third hours, and with milk in the last hour of secre- 

 tion. The point of maximum outflow as well as the whole curve of 

 secretion is always characteristic for each diet. On proteid in the 

 form of bread, five times more pepsin is poured out than on the same 

 quantity of proteid in the form of milk, and the flesh-nitrogen re- 

 quires 25 per cent, more pepsin than that of milk. These different 



