22 GENERAL ANATOMY OF THE FROQ 



a. The gall-bladder is a small spherical greenish sac lying 



between the right and left lobes of the liver. 



b. The bile duct is a slender tube leading from the liver 



and gall-bladder to the duodenum, into which it opens 

 about half an inch beyond the pylorus, and on the 

 inner or concave side of the loop formed by the duo- 

 denum and stomach. The distal half of the bile duct 

 traverses the pancreas : it has rather thick white walls 

 and is easy to see ; the upper half is more slender and 

 more difficult to trace. 



To trace the bile duct turn the liver forwards so that the point 

 of attachment of the gall-bladder is clearly seen ; and slightly 

 stretch the duodenum by a pin passed through the pylorus. De- 

 termine the position of the two ends of the bile duct from the 

 description given above, and dissect with a scalpel along the line 

 thus indicated. 



To see the opening of the bile duct, slit up the first three 

 quarters of an inch of the duodenum along its convex border and 

 wash out its contents : squeeze the gall-bladder so as to drive the 

 bile along the duct into the duodenum : note the point at which 

 it enters, and insert a bristle through the opening into the duct. 

 Notice also the strong wavy transverse folds of the mucous mem- 

 brane of the duodenum. 



3. The Pancreas. 



The pancreas is a whitish irregularly lobed mass lying in the 

 loop between the stomach and duodenum, and best seen by 

 turning the whole loop forwards. The pancreatic ducts are 

 numerous and open into the bile duct, which passes through 

 the pancreas to reach the duodenum. 



Cut through the mesentery along its attachment to the intestine : 

 uncoil the intestine, leaving it attached at both ends, and spread 

 'it out on your dissecting board : measure the lengths of the 

 several portions and draw tliem to scale. 



F. Other Abdominal Viscera. 



1. The Kidneys are two flat elongated oval bodies of a red 

 colour attached to the dorsal body- wall, close to the middle line, 

 one on each side of the backbone or vertebral column. They 

 lie in the large lymph space behind the peritoneum, and, like 



