1903.] Phenomena in Mammalian Non-medullated Nerve. 167 



conducted was 17 — 19° C, except where otherwise stated. The current 

 of injury was balanced against an equal fraction of a volt, and the 

 value read off. This compensation was maintained throughout the 

 experiment. No current, therefore, flowed through the nerve when at 

 rest. 



The experiments were ordinarily carried out in duplicate, with both' 

 medullated and nori-medullated nerves from the same animal. 



The electromotive phenomena are considered in the present paper 

 under two heads : — 



1. Negative variation. 



2. Electrotonic currents. 



1. Negative Variation. 



{Experiments.) 



The electromotive phenomena in the nerves of the horse resemble 

 those in the nerves of other mammalia in kind, but differ in degree, 

 being of considerably less magnitude.' 55 ' This is due, in part, to the 

 large amount of connective tissue surrounding the nerves, and forming 

 a derivation circuit. When this connective tissue is dissected off, the 

 effect on the galvanometer is increased. Three experiments may be 

 quoted on this point : — 



Table I. 



Experiment. 



Nerve. 



Current of 

 injury. 



Negative 

 variation. 



Notes. 



720 (A){£;; 



Median 



5> 

 ?5 



Splenic 

 ?» 



millivolts. 

 2 7 

 4-1 



8-2 



8- 5 



9- 7 

 11 '3 



millivolts. 

 0-172 

 0-309 



0-242 

 359 



0- 504 



1- 910 



Whole nerve. 

 Single nerve-bundle. 



The nerve was isolated in the usual way and the measurements made 

 that are marked a, the connective tissue was then dissected off as far as 

 possible, and the measurements b taken. Both injury current and 

 negative variation are increased, the latter more than the former. But 

 it will be noticed that even in the most favourable case the voltage of 

 the negative variation is less in the medullated nerves of the horse 



* This has already been observed in the case of the current of injury, see Gotch, 

 ' Schafer's Text-book,' vol. 2, p. 520, and Biedermann, ' Elektrophysiologie,' 1895, 

 p. 638. 



N 2 



