LABORATORY MANUAL OF PHYSIOLOGY. 



down with one hand, and the liver and lower ribs up with the other, 

 the junction of the oesophagus and stomach may be seen. 



6. Arrange an inductorium for weak tetanizing current. Place 

 the electrodes from the secondary coil under the superior laryngeal 

 nerve. Arrange a metronome or chronograph marking seconds. 

 This is to assist in taking the time of the swallowing move- 

 ments. 



The work of the experiment may be divided among four stu- 

 dents as follows : 



Let one student manage the stimulation of the superior laryn- 

 geal nerve or other nerves that it may be desired to stimulate dur- 

 ing the course of the experiment ; let another make the time ob- 

 servations of the swallowing movements; let a third manipulate 

 the stomach for observation of the lower end of the oesophagus; 

 and let a fourth make careful notes of the observations. 



7. Stimulate the superior laryngeal nerve with the weak tetan- 

 izing current until the rabbit swallows. Stimulation of this afferent 

 nerve brings about, among other things, a reflex swallow. Note 

 and time the beginning of the swallowing movement. Note the 

 passage of the peristaltic wave along the cervical portion of the 

 oesophagus, and the end of the peristaltic movement at the stomach. 

 How much time has elapsed between the beginning of the swallow 

 and the ending of the peristalsis at the stomach ? Repeat the ob- 

 servation a number of times. What is the average time occupied 

 by the passage of a peristaltic wave over the length of the oesopha- 

 gus in your rabbit ? 



8. Determine whether the mechanism of cesophageal peristalsis 

 is a nervous reflex one or due to muscular conduction of the con- 

 traction wave from one segment of the oesophagus to another. 



Tie two ligatures around the oesophagus, in the cervical region, 

 and cut completely through the gullet between the ligatures. Mus- 

 cular continuity is thus absolutely severed. 



While making observations, as before, produce a swallow by 

 stimulating the superior laryngeal. Does the peristaltic wave still 

 pass over the lower segment of the oesophagus to the stomach ? If 



