ANATOMY AND PHYSIOLOGY OF NERVOUS SYSTEM. 



661 



[n the case of a man who plunged his elbow into a freezing mixture, 

 as to greatly cool the ulnar nerve, there was no contraction, but 

 tin in the parts innervated by the nerve. 



CAN A NERVE-FIBER BE FATIGUED ? It has been shown by Bow- 

 litch that if you curarize an animal and irritate the nerve for 

 lours, when the curare paralysis of the motor nerve ends and has 

 >een removed a muscular contraction of undiminished force ensues. 



Fig. 264. D, Dubois-Reymond's Spring Myograph to , Measure the 

 Rapidity of the Nerve Current in Motor Nerves. (LAIIOUSSE.) 



P, Cell. W, Pohl's commutator. If, Muscle, n, Nerve irritated by an induc- 

 tion nearest to muscle. F, Writing pen attached to muscle, n', Nerve irritated 

 by an induction current farthest from muscle. B, Smoked plate on which are 

 recorded the movements of the writing pen F. 



lability to fatigue a nerve-fiber occurs in both medullated and 

 inmedullated nerves. 



The Transmission of the Nerve-wave. This demands that the 



jrve-fiber stimulated be entirely sound. It has the following phe- 

 lomena: The nerve-wave passes in both directions in both sensory 

 ind motor nerves. When a nerve is irritated by an electrical current 



le electromotive phenomenon of negative variation is seen in both 



