THE PANCREATIC JUICE 795 



authors extracts of the pancreas have the power of splitting off 

 choline from lecithin. It is not known whether the same property 

 is present in pancreatic juice itself, or whether any other dissociations 

 are brought about in the complex molecule of lecithin under the 

 action of this digestive fluid. 



THE SECRETION OF PANCREATIC JUICE 

 In order to study the relation of the secretion of pancreatic juice 

 to the other processes of digestion, observations must be carried 

 out on an animal with a permanent pancreatic fistula. Such a 

 fistula was established by Claude Bernard by bringing the duct of 

 the pancreas to the surface and inserting into it a lead or silver tube. 

 The arrangement was, however, unsatisfactory since after a few days 

 the tube dropped out and the natural course of the duct from pan- 

 creas to intestine was restored. In order to avoid the disadvantages 

 of this proceeding Heidenhain and Pawlow independently devised 

 another method to enable us to determine the causes of pancreatic 

 secretion. The pancreas in most cases possesses two ducts, the 

 upper one opening along with the bile duct, the lower one a short 

 way down. The relative sizes of these two ducts vary in different 

 animals, the lower one being larger in the dog, while in man and 

 the cat the upper one is the larger. In order to establish a pan- 

 creatic fistula in a dog, a small quadrilateral piece of the duodenal 

 wall is exsected, having the papilla of the lower duct opening in the 

 middle of its mucous surface. The integrity of the gut is restored 

 by suturing in a single line of stitches the margins of the wound 

 in the duodenum, and the exsected piece is brought to the surface 

 and stitched in the middle of the abdominal wound. The greater 

 part of the pancreatic secretion will escape by the fistula, and can 

 be collected either by the insertion of a cannula into the duct or by 

 attaching a glass funnel below its orifice. Great care has to be taken 

 in the after treatment of such animals. The pancreatic juice, which 

 flows over the papilla, acquires in so doing strong proteolytic powers, 

 and tends therefore to dissolve and irritate the adjacent abdominal 

 wall. This can be prevented by taking care to collect all the juice, 

 and to allow none to flow away over the surface of the body. Another 

 drawback is that the continual loss of pancreatic juice in many cases 

 seriously affects the animal's health. This may be obviated to a 

 certain extent by keeping the animal on a milk diet with the addition 

 of sodium bicarbonate to replace the loss of this salt by the juice. 

 With great care Pawlow has succeeded in keeping such animals in 

 a perfectly healthy condition. In the fasting condition there is, 

 as a rule, no secretion of juice, though the escape of a few drops may 

 be observed at long intervals. If a meal be administered to the 



