60 LAB OR A TOR Y G VIDE IN PH YSIOLOG Y. 



later stimuli but not to the first ones, one may con- 

 clude that in making the preparation a portion of 

 the central end of the nerve was killed. 

 (2) What may one conclude if the muscle responds 

 to stimuli applied to the central end of the sciatic 

 nerve, but later fails to respond to stimuli applied 

 farther along the course of the nerve, i. e., nearer the 

 muscle? 



b. Thermal Stimulation. 



(3) Make and mount a fresh preparation. Heat the 

 copper wire in a gas flame and touch the end of the 

 nerve with the hot wire. If the preparation has 

 been successful the muscle will respond by a contrac- 

 tion. If the preparation is a good one save at least 

 ^i of the nerve for the subsequent experiment. 



c. Chemical Stimulation. 



(4) Cut off the part of the nerve which is dead and 

 lay the central end of the still functional nerve in a 

 saturated solution of common salt. Await results t 

 Record all results. 



