v PRACTICAL DIRECTIONS 77 



the head) , and after making out the relations of the parts 

 already examined in situ (pp. 22 and 23), note 



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

 and cystic ducts, and the point at which it enters the duo- 

 denum (Fig. 1 8). 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 communi- 

 cation 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 neces- 

 sary) 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 peri- 

 toneum. 



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

 bladder firmly over one end of a wicle 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. 



