iv PRACTICAL DIRECTIONS 65 



of the gastrocnemius and pull it upwards or towards the thigh. Note 

 the result. 



3. In a freshly killed frog (see p. 103) expose the gastrocnemius as 

 directed above, and with the small forceps give a sharp pinch to the belly 

 of the muscle. Note the contraction following the stimulus. 



Then remove the skin on the dorsal side of the thigh, and separate 

 the muscles in this region so as to expose the sciatic nerve (Figs. 17 and 

 51). Trace this towards the shank and notice its branch going to the 

 gastrocnemius. Carefully separate the nerve as it traverses the thigh 

 and pinch it with the forceps, noting again the contraction following 

 the stimulus. 



PRACT Zooi 



