PANCREATIC JUICE. 247 



the pancreatic juice and dissolved in water, are capable of imparting to the 

 fluid the characters of the normal secretion (Bernard). 



The entire quantity of pancreatic juice secreted in the twenty-four hours 

 has been variously estimated by different observers. After what has been 

 said concerning the variations to which the secretion is subject, it is not sur- 

 prising that these estimates should present great differences. Bernard was 

 able to collect from a dog of medium size eighty to one hundred grains (5'2 

 to 6*5 grammes) in an hour ; but it must be remembered that only one of 

 the ducts was operated upon, and that the gland is very susceptible to irri- 

 tation. There is no accurate basis for an estimate of the quantity of pan- 

 creatic fluid secreted in the twenty-four hours in the human subject or of the 

 quantity necessary for the digestion of a definite quantity of food. 



Unlike the gastric juice, the pancreatic juice, under ordinary conditions 

 of heat and moisture, rapidly undergoes decomposition. In warm and 

 stormy weather, the alteration is marked in a few hours ; but at a tempera- 

 ture of 50 to 70 Fahr. (10 to 21 C.), the fluid decomposes gradually in 

 two or three days. As it thus undergoes decomposition, the fluid acquires a 

 very offensive, putrefactive odor, and its coagubility diminishes, until finally 

 it is not affected by heat. The alkalinity, however, increases in intensity, 

 and when neutralized with an acid, there is a considerable evolution of car- 

 bon dioxide. 



Action of the Pancreatic Juice upon Starches and Sugars. The action of 

 the pancreatic juice in transforming starch into sugar was first observed, in 

 1844, by Valentin, who experimented with an artificial fluid made by infus- 

 ing pieces of the pancreas in water. Bouchardat and Sandras first noted this 

 property in the normal pancreatic secretion. Amylopsine is undoubtedly the 

 substance concerned in the action of this fluid upon starch. 



The property of converting starch into sugar is possessed by several of 

 the digestive fluids. The starchy constituents of food are acted upon by the 

 saliva, and this action is not necessarily arrested as the food, mixed with the 

 saliva, passes into the stomach. The intestinal juice is also capable of effect- 

 ing the transformation of starch into sugar to a considerable extent. It 

 therefore becomes an important question to determine precisely how far the 

 pancreas is actually concerned in the digestion of this class of substances. 



Bernard placed the pancreatic juice at the head of the list of the digestive 

 fluids which act upon starch. This view is correct, although he was in 

 error in claiming that starch is digested almost exclusively by the pancreas. 

 Bernard's experiments, however, were made chiefly on dogs, and these ani- 

 mals do not naturally take starch as food. In man, some of the starchy 

 constituents of the food are acted upon by the saliva, but most of the starch 

 taken as food is digested in the small intestine. Although the intestinal 

 juice is capable of effecting the transformation of starch into sugar, the ex- 

 perimental evidence is conclusive that in this it is subordinate to the pancre- 

 atic juice, which latter effects this transformation, at the temperature of the 

 body, with great activity. It is possible that the bile assists in this process 

 to a slight extent. In the transformation of starch into sugar in the small 



