DIGESTION. 161 



Daily Quantity of the Gastric Juice. The quantity of gastric 

 juice secreted during a given time, like that of the saliva, varies much 

 according to the condition of the secreting organ. An exact estimate 

 of its daily amount is difficult for several reasons. First, if excited by 

 artificial irritation of the gastric mucous membrane, its quantity is not 

 so abundant as when produced by the natural stimulus of food ; sec- 

 ondly, if excited by the introduction of food, a part of it is absorbed 

 by the alimentary material, and consequently cannot be collected for 

 measurement ; and thirdly, the quantity collected during a short period 

 does not indicate the rate of production for the rest of the twenty-four 

 hours, because its secretion is influenced by the state of the digestive 

 process. Neither can we draw from a fistula all the gastric juice 

 obtainable during twenty-four hours, and consider that as representing 

 the normal daily amount ; because we should be taking away a quantity 

 of fluid which is naturally retained for reabsorption by the blood-vessels, 

 and its supply would be consequently diminished. But notwithstand- 

 ing these difficulties, sufficient facts have been collected to show that 

 the gastric juice is far more abundant than the other digestive fluids. 

 Beaumont obtained from the stomach of St. Martin, by the introduction 

 of a gum-elastic catheter, 44 grammes of gastric juice in fifteen minutes. 

 We have often collected from a medium-sized dog, at the beginning 

 of digestion, from 60 to 75 grammes in the same time. Bidder and 

 Schmidt, in a dog weighing 15.5 kilogrammes, obtained by separate 

 experiments, consuming in all twelve hours, 793 grammes of gastric 

 juice. If these experiments, as is probable, indicate the average rate 

 of secretion during the day, the entire quantity for twenty-four hours, 

 in an animal of that size, would be 1586 grammes; or about 100 

 grammes for every kilogramme of bodily weight. By applying this 

 calculation to a man of ordinary size the authors estimate the aver- 

 age daily quantity of gastric juice in man at about 6500 grammes. 

 Schmidt, in his case, already quoted, of a woman with gastric fistula, 

 obtained, as the mean result of several observations, 580 grammes of 

 gastric juice in the course of an hour. The secretion, however, was 

 much poorer in characteristic ingredients than that usually obtained 

 from the dog, and was also inferior in digestive power. 



Another method for estimating the daily quantity of gastric juice 

 is to ascertain the amount required for digesting the albuminous food. 

 According to Lehmann,* one gramme of coagulated albumen, calculated 

 as dry, requires for its solution 20 grammes of gastric juice. As the 

 .average daily consumption of albuminous matter in man is 130 

 grammes, this would require 2600 grammes of gastric juice per 

 day. Our own observations on the digestibility of fresh meat make 

 the daily requirement higher. A weighed quantity of fresh lean meat, 

 containing 78 per cent, of water and 22 per cent, of solid ingredients, 

 was cut into small pieces, and digested for ten hours, with frequent 



* Physiological Chemistry. London, 1853, vol. ii., p. 53. 

 L 



