THE KANSAS UNIVERSITY 

 SCIENCE BULLETIN. 



Vol. VII, No. 11] JANUARY, 19 1 3. [vo'^'xv.irNo n 



BLOCKING NERVE IMPULSES AROUSED IN CUT AND 



INTACT NERVES, AND IN STRYCHNINIZED 



AND NORMAL FROGS. 



BY CHARLES M. GRUBER. 



From the physiological laboratory of the University of Kansas, under the direction of 



I. H. Hyde. Ph. D. 



THE object of the investigation, of which a preliminary' 

 sketch follows, was to study the practical value of the tri- 

 polar block upon impulses aroused by different kinds of stimuli, 

 and to compare its efficiency and advantages with the nerve 

 blocks produced by other methods upon cut and intact nerves 

 in the frog. 



From many investigations it has been demonstrated that 

 nerve conduction may be inhibited by the same forces, but of 

 different degree, as those that arouse nerve impulses, and 

 effect stimulation, namely, mechanical (compression), chemi- 

 cal (cocaine and magnesium sulphate), thermal (freezing), 

 and electrical (either faradic or galvanic bipolar or tripolar 

 currents). 



The tripolar galvanic current is usually used for stimulation, 

 though it has in a few instances been employed to block vagus 

 impulses. In this investigation the tripolar current was 

 brought to the nerve by interpolating between the nonpolariz- 

 able electrodes and the nerve, zephyr fibers, moistened in 

 normal salt solutions. 



It was proved from the first that the bipolar method was 

 less efficient than the tripolar, and it was therefore abandoned. 



The stimulating current consisted of the minimal faradic 

 strength that caused a maximal contraction of the gastroc- 



Received for publication November 12, 1912. 



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