274 DIGESTION. 



great experimental facts upon which is based the view that the pancreatic juice has the 

 property of digesting the fats. Concerning the accuracy of this observation there can be 

 no doubt. The fact has been so frequently confirmed, that it must now be considered as 

 established beyond question, and we can add our testimony to its accuracy from personal 

 observation. It is true that some of the German physiologists have been unable to con- 

 firm these experiments ; but, by carefully following out the process indicated by Ber- 

 nard, which is detailed with great care, we have invariably found his observations to be 

 correct. It is well known that many of the German experimenters operated with pan- 

 creatic juice which was not coagulable and which Bernard regards as abnormal and in- 

 capable of digesting fat. 



The pancreatic juice is the only one of the digestive fluids which is capable of forming 

 a complete and permanent emulsion with fats. The fact that the other digestive fluids 

 will not accomplish this is easily demonstrated as regards the saliva, gastric juice, and bile. 

 The intestinal juice is then the only one which might be supposed to have this property. 

 The observations of Busch on this point, in his case of intestinal fistula, are conclusive. 

 He found that fatty matters taken into the stomach were discharged from the upper 

 opening in the intestine in the form of a fine emulsion and were never recognizable as 

 oil ; but that fat introduced into the lower intestinal opening was not acted upon and 

 was discharged unchanged in the faeces. 



Another peculiarity noted by Bernard in the emulsion resulting from the action of 

 pancreatic juice upon fats is that it persists when diluted with water and will pass 

 through a moistened filter like milk. This does not take place in the imperfect emulsion 

 formed by a mixture of oil with any other of the digestive fluids. 



Although the normal pancreatic juice is constantly alkaline, this is not an indispensa- 

 ble condition as regards its peculiar action upon fats ; for the emulsion is none the less 

 complete when the fluid has been previously neutralized with gastric juice. 



Bernard has shown that the pancreatic juice and the tissue of the pancreas have the 

 property of saponifying fats, or decomposing them into a fatty acid and glycerine, and that 

 this property is not possessed by any other tissue or liquid of the economy. The question 

 naturally arises, then, whether this be an accidental property of the tissue and the secre- 

 tion of the pancreas or whether partial saponification of fat take place in digestion. Con- 

 cerning this point there is no difference of opinion among physiological chemists. The 

 fat which is contained in the lacteal vessels is always neutral ; and the absence of any 

 fatty acid has been recognized by Bernard as well as by others. The inevitable conclu- 

 sion to be drawn from this fact is, that, while fat may be in part decomposed into an acid 

 and glycerine by the pancreatic juice, out of the body, in the natural process of digestion, 

 either this does not take place or the acid is not absorbed by the lacteals. The greatest 

 part, if not the whole, of the fat which is digested in the small intestine is simply formed 

 into an emulsion by the pancreatic juice and undergoes no chemical alteration. 



To complete the experimental evidence of the action of the pancreatic juice in the 

 digestion of fats, Bernard attempted to extirpate or destroy the pancreas in a living ani- 

 mal. This he found very difficult. All attempts to extirpate the organ with the knife 

 being unsuccessful, the injection of foreign matters into the duct was resorted to. After 

 a great number of unsuccessful experiments, in two instances, the functions of the gland 

 were suspended for a time and its tissue was partly destroyed by the injection of melted 

 tallow. In both of these observations, the effects upon digestion were very marked. 

 Although the appetite was voracious, the animals became gradually emaciated, and the 

 faeces contained a large quantity of rancid, undigested fat. At the same time, other ali- 

 mentary principles, incompletely digested, were recognized in the discharges. In two 

 dogs operated upon by Bernard, in which the experiments were successful, the nutrition 

 and the alvine discharges became normal at the thirteenth and the seventeenth day. 

 After the animals had completely recovered, they were killed, and the pancreas in both 

 instances was found partially destroyed. 



