THE DIGESTIVE SECRETIONS 



933 



the duodenum separately at a distance of 2 to 3 cm. above the former. 1 In some 

 animals the duct of Wirsung unites with the common bile duct shortly before its 

 entrance into the duodenum. This accounts for the fact that tumors, affecting 

 the head and body of the pancreas, very frequently give rise to a stagnation of the 

 bile. Thus, a slowly developing jaundice, which is associated with a loss of appetite 

 and indigestion, but no pain, almost always indicates a carcinoma of the pancreas. 

 In the dog, the blood-supply of the pancreas is derived from the mesenteric, 

 pancreatico-duodenal and splenic arteries. The first supplies its head-region, 

 the second its body, and the third its tail. The venous return is effected by three 

 channels of which the vena pancreatica is the largest. The latter joins the portal 

 vein a short distance below the hilum of the liver. A small portion of its blood is 

 returned by way of the splenic and mesenteric veins, but this also enters the portal 

 vein. The nerve-fibers innervating this organ arise in the mesenteric and celiac 

 ganglia of the solar plexus and follow the highways of the aforesaid arteries. Pre- 

 ganglionically, connection is made with the central nervous system by way of 

 the vagi ami splanchnic nerves. 



Histological Changes in the Cells of the Pancreas During Secre- 

 tion. In 1856 Cl. Bernard observed in fresh preparations of the pan- 



FIG. 496. A TERMINAL LOBULE OF THE PANCREAS OF THE RABBIT. (Kuhne and Sheridan 



Lea.) 

 A, in resting condition ; B, after active secretion. 



creas of the rabbit that two-thirds of the inner zone of its cells are 

 taken up by a dense granular material which he believed to be the 

 mother-substance of the active principles of the pancreatic juice. 

 Later on Kuhne and Lea 2 succeeded in showing that the activity of 

 this gland is associated with a loss of at least a part of this material. 

 The cells become smaller in size and eventually exhibit a perfectly 

 clear basal zone. While these changes may be rendered more con- 

 spicuous by the use of pilocarpin and secretin, their complete develop- 

 ment frequently necessitates several injections of these drugs until 

 the flow of pancreatic juice has almost ceased, owing to an exhaustion 

 of the secretory material. While the normal gland possesses a yellow- 

 ish-white color, it then becomes transparent, soft, and pink in color. 

 Methods Employed to Procure Pancreatic Juice. The best way 

 in which pancreatic juice may be obtained, is to establish a fistula 



1 Opie, Diseases of the Pancreas, London, 1903, and Gegenbaur, Anatomic des 

 Menschen, Leipzig, 1899. 



2 Unters. aus dem physiol. Inst. zu. Heidelberg, 1882. 



