LABORATORY MANUAL OF PHYSIOLOGY. 



Note the slight opening and closing of the glottis with inspiration 

 and expiration. While observing the movements of the vocal 

 bands, stimulate one inferior laryngeal nerve. What is the effect 

 on the vocal bands? Stimulate both nerves at the same time. 

 What is the effect on the movements of the vocal bands ? 



14. Stimulate the superior laryngeal nerves in the same way and 

 note the effect, if any, on the vocal bands. 



15. To determine the time occupied for the passage of a liquid 

 from the mouth into the stomach, in man, proceed as follows: 



Arrange a drum with smoked paper for medium slow revolution. 

 Set up a chronograph to mark seconds on the drum. Place a short- 

 circuiting key in circuit with the time marker. When the key is 

 closed, the lever of the time marker will write a straight line. When 

 the key is opened, a time tracing, in seconds, will be recorded. 

 Take a fellow-student into a quiet room and listen with a stetho- 

 scope over the end of the sternum. Start the drum. Let the sub- 

 ject of the experiment take one swallow of water. You will hear 

 two sounds, one when the liquid is shot into the oesophagus, the 

 other when the liquid enters the stomach. When the first sound 

 is heard, open the short-circuiting key. When the second sound is 

 heard, close the key. How many seconds have elapsed between the 

 two sounds ? 



V. GASTRIC DIGESTION. 



1. Tests for Proteids. (a) Coagulation by Heat. Prepare 

 solutions of the following proteids: A, egg albumin, dilute; B, 

 acid albumin in acid solution. This is obtained by subjecting 

 some dilute egg albumin to the action of o.2-per-cent HC1 for sev- 

 eral hours at body temperature. Neutralizing with an alkali will 

 precipitate the acid albumin from its solution. 



C, myosin, dissolved in a lo-per-cent NaCl solution. This may 

 be prepared by mincing lean meat, freeing from blood by repeated 

 washings, and extracting the myosin by an ammonium-chlorid 

 solution. The salt may be removed by dialysis, leaving the myosin 

 as a gelatinous mass, or it may be precipitated by diluting the solu- 



