120 STUDIES IN CLINICAL PHYSIOLOGY 



was started by secretin, which in its turn depends 

 on the amount of HCl coming through from the 

 stomach. A still more disturbing factor is the action 

 of the ferment in the intestinal juice called entero- 

 kinase, without which trypsin is inert, being secreted 

 in an inactive form called trypsinogen and only 

 activated by the enterokinase. More recent work, 

 taking these new facts into account, shows that the 

 composition of the pancreatic juice does not vary. 

 It is probable, however, that other substances besides 

 hydrochloric acid have the power of calling forth 

 pancreatic juice, and, indeed, if it were not so, 

 patients with cancer of the stomach would usually 

 starve. Workers in Pawlow's laboratory have 

 demonstrated that the most important of these are 

 fat and soaps, and the action is similar to that of 

 the gastric juice, namely, by exciting the formation 

 of a secretin. It is very probable, also, that the 

 sight and smell of food set up a flow of pancreatic 

 juice, but it is difficult to be sure of this. 



Pawlow's operative experience in making pancreatic 

 fistulae in dogs and in the after-treatment may 

 suggest devices for surgical practice. To obtain a 

 permanent fistula it was necessary to bring the duct 

 out on the abdominal wall, and still to preserve its 

 natural orifice, other\\'ise it closed rapidly. Therefore 

 a small square of duodenum containing the opening 

 of the duct was transplanted to the skin. With 

 careful nursing and treatment, such dogs would Hve 

 for months or years. 



There were two principal points in the after-treat- 

 ment. At first there was great difficulty on account 



