ETHER, ETHYL CHLORIDE 



57 



What relation do the optic lobes of the frog bear to the cere- 

 bellum of mammals? 



3. Learn the technic of pithing a frog if you have not al- 

 ready done so. (See Fig. 49.) 



Ether, Ethyl Chloride, Chloroform, Ethyl Bromide. 

 (Irritability and Conductivity of Nerve.) 



4. (a) After pithing place a frog face downward on the 

 frog board and dissect out the sciatic nerve from its origin 



To muscle lever* 

 To -Secondary coil 



Fig. 50. Harvard moist chamber. 



at the spinal cord down to the knee. Avoid injuring the 

 nerve. Tie a thread to the nerve and then dissect the gas- 

 trocnemius muscle (Figs. 47 and 60) loose from the bones 

 of the leg. Out the tendo Achillis long and then divide the 



