Electromotive Phenomena of Non-medullated Nerve. 381 



only while the nerve was quite fresh could such responses be obtained 

 by single stimuli. The momentary mechanical stimulus consisted in a 

 clean cut through the nerve with fine sharp scissors, the blades of 

 which had been moistened with normal saline ; the nerve was supported, 

 so that there should be no pull upon the led-ofF portion. 



In the tables of experiments given below, a few cases will be noticed 

 in which there is a back swing + beyond the position of rest. This 

 is partly instrumental swing, but partly also due to a slight positive 

 after-effect. The galvanometer used, although highly damped, was 

 not perfectly dead-beat, and the small after-effects could not be accu- 

 rately estimated. All that can be said is that there is a slight ten- 

 dency towards positive after-effects on good nerves when quite fresh ; 

 later the back swing tends to fall short of the position of rest. 



With tetanising induction currents the positive after-effect was only 

 once observed with any certainty. 



Olfactory Nerve of Pike. — Nerve current compensated. The nerve 

 current is + , the iiegative variation - , on the scale throughout the 

 experiments. 



Exp. 1.— March 8, 1899. Pike, weighing lbs. Nerve I. Stimu- 

 lation by single break induction shocks. 



Coil 

 distance. 



Position 

 of rest. 



^Negative 

 variation. 



Back 

 swing. 



Yalue of 

 neg, vai". 



Back swing + or — *, 



cm, 

 j> 



71 



63 

 51 



C9-5 

 61 5 

 52-7 



71 -7 



t;3 -2 



54-4 



-1-5 

 -1-5 

 -1-5 



+ 0-1 

 + 0-2 

 + 0-4 







cm. 



5J 

 ) J 



47 

 41 

 45 



45 -G 

 39-7 

 43-7 



46-7 

 40-7 

 44-5 



-1-4 

 -1-4 

 -1-3 





-0-3 

 -0-3 

 -0-5 



Nerve moistened. Stimulation by single make induction shocks. 



cm. 



49 

 47 



4S 

 45-9 



49 -6 

 46 -2 



-1 

 -1 1 



+ 0-6 



-u'-8 



Same nerve. Ten stimuli make and break alternately at half- 

 second intervals. 



cm. 



J5 



3S-5 

 49 



27-7 

 38 -6 



36 -8 

 47 



-10-8 

 -10-4 





-1-7 

 -2 



* In this column the + sign signifies a back swing beyond the position of rest, 

 the — sign signifies that the back swing fell short of that position. 



