THE KANSAS UNIVERSITY 

 SCIENCE BULLETIN. 



Vol. VII, No. lOJ JANUARY, 1913. n^ol^xvn.No.' 



A COMPARISON OF NATURALLY AND ARTIFICIALLY 



AROUSED IMPULSES UNDER THE INFLUENCE 



OF NERVE BLOCKS. 



BY CHARLES M. GRUBER. 

 From the physiological laboratory of the University of Kansas. 



THE research, of which a preliminary report is here pre- 

 sented, was begnn by Doctor Hyde several years ago, at 

 the suggestion of Dr. C. S. Sherrington, in his laboratory in 

 the LTniversity of Liverpool, and was completed by one of 

 Doctor Hyde's research students. 



It was conclusively proved by me that impulses aroused by 

 artificial stimuli in a frog's sciatic nerve can be suppressed 

 by the tripolar electrical block, liquid air, and other blocking 

 agencies, and that the tripolar block could be repeatedly in- 

 troduced in the circuit without injury to the neiwe's function. 

 Also that afferent impulses could be inhibited with weaker 

 currents than could the efferent impulses. It was of interest, 

 therefore, to ascertain whether natural impulses originated 

 by higher centers in the brain were physically of the same 

 nature as those electrically produced, and could be suppressed 

 by the same kind and str,ength of block as could those arti- 

 fically aroused by the electrical current. 



The experiments were conducted on the phrenic nerves in 

 rabbits. By means of a modification of Head's method, records 

 of the movements of the diaphragm and the thoracic wall were 

 obtained. The artificial stimuli were the threshold strengths 

 of the faradic currents applied to the phrenic nerve and its 

 branches; the movements of the diaphragm in response to 



Received for publication November 12, 1912. 



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