v PRACTICAL DIRECTIONS 77 



lobes of the liver forwards (i.e., towards the head) and after making out 

 the relations of the parts already examined in situ (pp. 20 23), note 



The common bile-duct, formed by the union of the hepatic and cystic 

 ducts, and the point at which it enters the duodenum (Fig. 18). Make 

 a small slit in the duodenum just opposite its entrance, and gently squeeze 

 the gall-bladder between your finger and thumb, so as to force a drop of 

 bile into the intestine. (The pancreatic duct and its communication with 

 the bile-duct cannot easily be made out by dissection). Sketch the whole 

 dissection. 



Now remove the liver, unravel the intestine by tearing through the 

 mesentery, and lay open the enteric canal by inserting one blade 

 of the scissors into the gullet, and cutting through the whole tube in a 

 longitudinal direction. Test the contents of the stomach and intestine 

 with litmus paper (for this experiment a freshly killed frog is of course 

 necessary) and then pin out your dissection with the inner surface 

 upwards, wash it under the tap, and examine under water with a 

 magnifying glass. Make out 



1 . The cardia, pylorus, and pyloric valve. 



2. The mucous membrane, and its different appearances in the stomach, 

 small intestine, and large intestine. 



3. The muscular layer, covered externally by the peritoneum. 

 Make a simple dialyser (p. 73) by tying a piece of wet bladder firmly 



over one end of a wide glass tube about six inches long. Into this put a 

 solution of sugar or salt, and immerse the tube up to the level of the 

 solution in a rather larger vessel of distilled water, and leave it for a 

 short time : taste the water in the outer vessel. Then place some white 

 of egg in the dialyser, and test for albumen by heating some of the water 

 in the outer vessel over a flame : if albumen is present, it will become 

 coagulated and form a cloud in the water. 



