STIMULATION OF MUSCLE AND NERVE 97 



curarization is best accomplished by the injec- 

 tion of curare into the dorsal lymph sac of a 

 frog the brain of which has been destroyed. 

 Wrap the frog in the cloth, head out. Hold the 

 frog with the fingers of the left hand, pressing 

 down the tip of the frog's nose with the left 

 thumb. Pass the right forefinger along the mid- 

 dle line of the head. A slight depression will be 

 felt at the joining of the skull and trunk. Here 

 the cerebro-spinal canal has no bony covering. 

 Make at this point a cut about a centimetre 

 (I inch) long through the skin in the middle line. 

 Thrust the seeker vertically through the soft 

 tissues until the point is stopped by the bony 

 vertebrae. Turn the point of the seeker towards 

 the head, and push it along the brain cavity, 

 moving it gently from side to side. 



Paralysis of Voluntary Motion by Curare. 

 Make a very small hole in the skin of the back 

 into the dorsal lymph sac. With a fine glass 

 pipette inject a few drops of a straw-colored 

 solution of curare. The curare of commerce is 

 the dried juice of a species of strychnos. It is 

 not a definite chemical compound and cannot 

 therefore be given in an accurate dose. It is 

 customary to make a one per cent solution of the 

 crude mass. This solution may be kept from 

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