DIGESTION IX THE SMALL INTESTINE. 407 



up into a state of emulsion, while a small quantity undergoes chemical 

 changes, in which fatty acids are liberated. The fatty acids thus liber- 

 ated combine with the alkaline bases of the bile and pancreatic juice to 

 form soaps. If oil, butter, or lard is stirred with pancreatic juice at a 

 temperature of 35 or 40 C., almost immediately a thick, creamy emul- 

 sion is formed which will stand for a long time. The presence of gastric 

 juice, even when in sufficient amount to neutralize the alkalinity of the 

 pancreatic juice, is stated by Bernard to have no influence on the emulsi- 

 fying property of this secretion ; but to produce it in its highest degree 

 the secretion must be normal, and that obtained from permanent fistula? is 

 much less efficacious than that from temporary fistulas. This emulsifying 

 power possessed by the pancreatic juice is due to the specific action of a 

 special ferment, termed generally the emulsive ferment, which is claimed 

 by Bernard to first emulsify and then saponify fats. It is certain that in 

 the small intestine the principal change is merely due to the production 

 of an emulsion, and nearly all the fat taken up by the absorbent vessels of 

 the small intestine is in the form of an emulsion and not of a soluble soap, 

 although both changes do occur in the small intestine ; the saponification 

 is, however, most marked after the fats have been absorbed. The emulsive 

 ferments, it has been claimed b}< Paschutin, may be readily extracted from 

 the pancreas by a solution of bicarbonate of sodium, and this solution 

 will readily emulsify fats. It is doubtful as to w r hat importance is to be 

 attached to this statement, since it has been already stated that a solu- 

 tion of bicarbonate of sodium constitutes an extremely delicate test 

 for the presence of fatty acids, and when such acids are present the 

 addition of the bicarbonate of sodium w^ill almost instantly form a per- 

 manent emulsion. Since, therefore, it is almost impossible to obtain fats 

 which are absolutely free from the presence of fatty acids, the above 

 statement is not by itself sufficient to prove that the emulsifjang power 

 of pancreatic juice is due to the action of a specific ferment. Other 

 proof is, however, found in the fact that the action of fresh normal pan- 

 creatic juice on neutral fats does result in the development of free fatty 

 acids and glycerin. This result may even take place when the pancreatic 

 juice has been diluted with twelve times its volume of water ; and although 

 gastric juice and hydrochloric acid seem to interfere with this action of 

 the secretion, the bile appears to facilitate it. Just as we found that the 

 solution of fibrin with acid in contact with peptic glands was a reliable 

 test for the presence of pepsin, so also the power possessed by the pan- 

 creas of decomposing fats and forming fatty acids and glycerin serves 

 for the recognition of the pancreas in lower animals, and, as emplo3 T ed 

 with this object in view, has been highly perfected by Bernard. 



The emulsive action of the pancreatic juice is destroyed by boiling, 

 and the digestive action on fats through the influence of pancreatic 



