ACTION OF THE PANCREATIC JUICE. 559 



The effects of the pancreatic juice on fatty matters have been 

 shown by experiments out of the body, and by observations on living 

 animals. If either the fluid obtained fresh from pancreatic fistulae 

 in animals, or a watery infusion of the substance of the gland just 

 taken from an animal killed during the digestive process, be agitated 

 with a neutral fat, and the mixture be maintained at a temperature of 

 100, the fatty substance is most perfectly emulsified, the action being 

 much more complete and durable than if saliva, bile, intestinal juice, 

 or any other animal fluid, had been employed. The emulsion lasts as 

 long as eighteen hours, after which the fat separates. It is found, 

 however, that a portion of the olein, margarin, and stearin, is now de- 

 composed, having been rapidly separated into the corresponding fatty 

 acids and glycerin. These effects are most marked when the pancre- 

 atic juice is collected a short time after digestion has begun, all the 

 characters of the secretion being then most evident. 



This remarkable decomposition is usually attributed to the pancre- 

 atin, combined with the operation of the free alkali of the fluid, just 

 as pepsin with an acid, effects the transformation of albuminoid sub- 

 stances. The pancreatic juice no longer possesses this power of de- 

 composing neutral fats into their fatty acids and glycerin, in the pres- 

 ence of ordinary acids, which destroy its alkalinity ; hence it has been 

 urged, that the acidity of the chyme must prevent this peculiar de- 

 composition. But the pancreatic fluid and the intestinal juice are 

 strongly alkaline, and moreover, the bile may here interpose, and, by 

 means of the soda present in combination with its conjugated acids, 

 may neutralize the acids of the chyme, and so permit the decomposi- 

 tion of the neutral fats of the food by pancreatic juice ; for this pro- 

 cess may not be interfered with by the acids of the bile, which are 

 themselves fatty. That the action of the pancreatic juice is, in some 

 important way, aided by the bile, and conversely, that the action of 

 the bile is seconded by that of the pancreatic juice, is highly probable, 

 from the fact that they are discharged into the intestinal canal so near 

 together, generally, indeed, at a common orifice. 



It happens, however, that in the rabbit, the chief pancreatic duct 

 enters the small intestine rather more than twelve inches below the 

 bile duct, which opens as usual a little below the pylorus ; another 

 smaller duct also exists, but it is almost impermeable. This arrange- 

 ment has been taken advantage of, in physiological experiments on 

 the use of the pancreatic fluid. The most interesting and important 

 of these, is one originally performed by Bernard, and since repeated 

 by others. A rabbit is crammed with fat, or its stomach is injected 

 with oily matter, and it is afterwards killed, whilst digestion is going 

 on; it is then found that the fatty matters in the intestine, above the 

 entrance of the pancreatic duct, though mixed with the bile, are yet 

 unchanged ; whilst below that point they begin to be emulsified; more- 

 over, the lacteals, or absorbent vessels of the intestine, above the point 

 of entrance of the pancreatic duct, although bile is there mixed with 

 the food, are filled only with a clear transparent fluid, and, indeed, 

 are mostly invisible ; whilst, at a point immediately below the entrance 

 of the pancreatic duct, those vessels are charged with their character- 



