SECRETION DIGESTION ABSORPTION. 



Place in the incubator for twenty minutes: At the end of this time 

 remove and test the mixture for peptones. Has any of the proteid 

 been digested ? 



(;;z) Add some saliva to a starch solution in a dialyzer tube of 

 parchment paper for twenty-four hours in the incubator. At the 

 end of this time test the water surrounding the dialyzer for re- 

 ducing sugar and for starch. 



IV. MECHANISM OF SWALLOWING. 



1. Inject a solution of 0.03 gram morphine sulphate under the 

 skin of a medium-sized rabbit. Anaesthetize lightly with ether. 

 Tie the rabbit, back down, upon the rabbit-board, with the neck 

 well stretched out. Clip and shave the hair in the neck region and 

 also over the epigastrium and zvphoid appendix. 



2. Make a median incision through the skin and fascia of the 

 neck. Separate the sterno-hyoid muscles and expose the trachea. 

 Carefully separate the trachea from the oesophagus, which lies be- 

 hind it, avoiding injury to the nerves and vessels running beside 

 and between the two. 



3. On either side of the trachea and between it and the oesopha- 

 gus, a fine nerve filament will be seen. These are the recurrent 

 laryngeal nerves. Pass a loop of thread around each recurrent 

 laryngeal nerve, but do not tie. Isolate the vagus nerve of each side 

 and secure with untied threads. Follow the vagus on one side as 

 far as the level of the lower part of the thyroid cartilage. At this 

 point it is joined by the superior laryngeal nerve. Isolate and 

 pass a loop of thread around this nerve. 



4. Pass a heavy ligature around the trachea as low in the neck 

 as practicable. Cut between the rings of the trachea just above 

 this ligature. Introduce a tracheal cannula and tie it in with the 

 ligature. Excise the piece of trachea between the cannula and the 

 cricoid cartilage. This brings the oesophagus w^ell into view. 

 Pass two threads around the oesophagus, to be tied later. 



5. Now make a median incision through the abdominal wall in 

 the median line and expose the stomach. By pulling the stomach 





