THE ACID EFFECT UPON PANCREATIC SECRETION. 117 



happens in the fluid. In normal digestion, however, the alkalinity of 

 the blood is increased. The food of the stomach, by virtue of its hydro- 

 chloric acid, calls forth the secretion of pancreatic juice, which in its 

 turn is derived from the blood. The increased alkalinity of the blood 

 during digestion is also in harmony with the well-known fact that the 

 alkaline content of the urine is greater during the same period, conse- 

 quently diametrically opposite changes would occur in the blood, accord- 

 ing as the pancreas is excited to action by acids introduced from without 

 or by that prepared in the stomach. From these theoretical considera- 

 tions alone we are therefore unable to admit an acid effect through the 

 medium of the blood. But we are in possession of direct experiments 

 which speak in the same direction. When acid solutions are injected 

 into the rectum the pancreas remains in perfect rest. In the same 

 way, acids do not act on the pancreas if they continue in the stomach 

 without entering the intestine. This fact was first indicated by Dr. 

 Gottlieb, but the question has since been more fully investigated by 

 Dr. Popielski. Here is one of his experiments on a dog with a per- 

 manent pancreatic fistula: 



the mucous membrane, and is not obtained from the ileuin. A saline extract 

 yields an inactive precursor of the substance, " prusecrrtln" which becomes 

 effective when treated with acid. Popielski, Wertheimer and Lepage had previously 

 shown that the acid was effective after severance of the duodenal and pancreatic 

 nerves. 



