288 STUDIES IN ADVANCED PHYSIOLOGY. 



transverse colon, and a descending section on the left side 

 known as the descending colon, which then finally through 

 the rectum communicates with the exterior. 



7. THE PANCREAS. 



The pancreas is a long, slender gland of reddish yellow 

 color and lies immediately below and back of the stomach 

 in the first fold of the duodenum. It is about five or six 

 inches long and from three-quarters to an inch in thickness. 

 In structure this gland resembles very closely the salivary 

 glands, being of the compound racemose type. The secret- 

 ing cells have the characteristic glandular appearance and 

 are so large as to practically fill the lumen of the tubes. 

 Examined under the microscope the cells at rest may be 

 seen to be more or less filled with trypsinogen granules, 

 while when examined after a period of activity the cells 

 seem clear. In both cases, however, the lumen of the tube 

 is exceedingly small. A large duct runs from one end of 

 the gland to the other and collects all of the pancreatic 

 juice, carrying it to the duodenum. This central duct 

 may be easily seen with the unaided eye as a whitish tube, 

 receiving along its course innumerable smaller branches 

 from the tubules which it passes, and finally, in conjunc- 

 tion with the bile-duct from the liver flows at an oblique 

 angle through the muscular wall of the intestine and pours 

 its secretion into that organ. This duct is called the pan- 

 creatic duct, or the duct of Wirsung. Sometimes an acces- 

 sory duct is given off which opens into the duodenum about 

 an inch or more above the main pancreatic duct. Indeed, 

 in some instances this accessory duct may become larger 

 than the main duct. This accessory duct is called the duct 

 of Santorini. The pancreas is richly supplied with blood- 

 vessels from the coeliac axis, and lymphatics and nerves 

 may be easily traced to it. On account of its action on 

 starches the pancreas is called by the Germans the "ab- 

 dominal salivary gland." Not infrequently it is referred to 

 by our butchers as the abdominal sweetbread, in this case 



