INTRODUCTION. 



see the flesh twitch or quiver in various parts. 

 This is the contraction or twitching here and there 



FIG. 1. 

 B 



/ 



W 



of the muscles, whose irritability is affected by the 

 cold air, the cold air acting as a stimulant. If you 

 now pinch one of the muscles, or prick it with a 

 pin, it will quiver or contract. The same would 

 occur if you applied galvanism to it. 



The natural stimulants of the muscle are the 

 nerves (Fig. 1. n n) the little white cords which you 

 see running in various directions among the muscles 

 or flesh and which come from the brain and the spinal 



B 2 



