DIGESTION. 171 



compared with the other digestive fluids. In the ox, cow, and horse, 

 Colin found the average quantity nearly the same, corresponding to 

 about 0.58 gramme per hour for every kilogramme of bodily weight. 

 Schmidt found it, in the dog, not more than 0.2 gramme per kilogramme 

 per hour. In the most successful instances, we have found it, in the 

 dog, as much as 1.25 gramme per kilogramme per hour during diges- 

 tion, but much less than this in the intervals. If we take, as the 

 average of these estimates, 0.5 gramme per hour for every kilo- 

 gramme of bodily weight, it would give for a man of medium size 

 about 800 grammes as the entire quantity secreted per day. 



The condition of the pancreas varies at different periods correspond- 

 ing with the activity of its secretion. In the intervals of digestion it 

 is pallid and dense ; during digestion it becomes turgid and vascular, 

 its ruddy color showing the increased quantity of blood in its vessels. 

 According to most observers, the ferment which effects the solution of 

 albuminous matters can only be extracted from the pancreas of animals 

 killed during the height of digestive action, which, in the dog, is from 

 five to seven hours after the ingestion of food. When digestion comes 

 to an end, the vascularity of the pancreas diminishes, and the organ 

 returns to its quiescent condition. . This periodical excitement at the 

 time of functional activity is observable, not only in the pancreas, but 

 in all parts of the digestive apparatus. 



Physiological Action of the Pancreatic Juice Among tne most j 

 important effects produced by pancreatic juice in digestion is the emul- ? 

 sification of the fats. This action is prompt and efficient when oil ' 

 is mixed with pancreatic juice in a test-tube, quite unlike anything 

 obtained by similar experiments with saliva, gastric juice, or bile. 

 Bernard found that the fresh pancreatic juice of the dog, at 38 C., 

 would form a complete and permanent emulsion with olive oil, butter, 

 suet, or lard, when mixed with either of these substances in the pro- 

 portion of one gramme of oleaginous matter to two grammes of 

 pancreatic juice. In the horse, ass, ox, sheep, and pig, according to 

 Colin,* this property of the pancreatic juice is in proportion to the 

 amount of its albumenoid matter ; one part of oil requiring for com- 

 plete emulsion from two to three parts of pancreatic juice when its 

 organic ingredients are abundant, and four, five, or six parts when they 

 are in smaller quantity. 



Within the alimentary canal the emulsive action of the pancreatic 

 juice is equally well marked. The fats are not affected by either saliva 

 or gastric juice ; and examination shows that they are unchanged in 

 their essential characters so long as they remain in the stomach. In 

 this organ they are simply liquefied by the warmth of the body, and 

 set free by the solution of their albuminous envelopes ; and they are 

 still visible in larger or smaller drops on the surface of the alimentary 

 mass. But almost immediately after passing into the intestine, the 



* Physiologic Coraparee des Animaux domestiques. Paris, 1854, tome i., p. 644. 



