Electromotive Phenomena of Non-medullated Nerve. 385 



ihamber with inlet and outlet tubes, and was led off in the usual way. 

 The stimulation by platinum wires was given at one minute intervals. 

 After a few normal responses — the character of which was a large 

 negative deflection often with incomplete return to the position of 

 rest — carbon dioxide was driven into the nerve chamber ; its immediate 

 effect was a marked diminution of the negative variation and the 

 a,ppearance of a positive after-variation, which increased in size for 

 several minutes, attaining often as much as three times the size of the 

 negative variation. At this point of highest development of the 

 positive after-effect, the back swing was very rapid, and began before 

 the close of stimulation. The positive after-effect then began to pass 

 off, and a few minutes later the deflection was once more purely nega- 

 tive. Larger doses of carbon dioxide produced anaesthesia of the nerve, 

 but with returning excitability the positive after-effect appeared as 

 above described. 



At the period when the distinct positive after-effect had passed off 

 a curious phase was sometimes noticeable immediately after stimula- 

 tion, viz., a quick to-and-fro movement, suggesting the struggle of two 

 opposing processes before the slow return of the spot of light towards 

 its position of rest. For instance, in the last line of figures in 

 Experiment 6 the spot stands at 19'5 ; on stimulation it moves 

 - to 9*5, then after the stimulus + to 11, - to 10, and slowly back 

 to 18. 



April 13, 1899. Olfactory Nerve 1. Stimulation by Tetanising 

 Currents. Nerve Current off' Scale Spot, brought back by Magnet. 



Stim. 



Coil. 



Zero. 



Neg. rar. 





Back 



Value 

 of 



neg. yar. 



Back swing. 





swing. 



+ or 



Incomplete. 



5" 



5 crj. 



70 



33 





63 



-37 





Less 7 



At 1 min. 





62 



29 





5G 



-33 







intervals. 





55 



23 





50 



-:32 









M 



50 

 43 



18-5 

 31 





42 



mins. 

 '48 -5 



-31-5 

 -11 



+ 6-5 



» 8 







4-J -5 



40 -5 





47-5 



- 2 



+ 5 





Exp. 6. . 



>) 



51 



45 





59 



- 6 



+ 8 









43* 



30 





67-5 



- 7 



+ 24 -5 









37=^- 



28 





61 



- 9 



+ 24 







JJ 



34 



24 





45 



-10 



+ 11 









29 



14 





29-5 



-15 



+ 0-5 









25 



8 





23 



-17 





2 





)3 



21 



4 





19 



-17 





„ 3 



* Tlie + after effect began before ihe end of stimulaticn. 



