388 Miss S. C. M. Sowton. Ohservations on the 



Fig. 6 is a photographic record of a similar experiment. • 



Fig. 6. 



Effect of CO2 on the negative variation of non-medullated nerve. Stimulation 

 at 1-minute intervals. 



Another condition in which the olfactory nerve gave positive after- 

 effects was after being kept for some time in normal saline. Isolated 

 grey nerve appears to be far less resistant than white nerve, but the 

 olfactory sometimes retained its excitability for as long as four hours 

 after excision, and the electrical response of such a kept nerve was 

 usually a negative effect followed by a large positive after-effect. In 

 frog nerve there is also a development of positive after-effect in stale 

 nerve ; but whereas such effects are in this case markedly reduced if 

 not abolished by a new transverse section, in the case of the olfactory 

 nerve the positive after-variation persists after fresh section. 



A few experiments were made to test the effect of ether and chloro- 

 form vapour on the negative variation of non-medullated nerve. The 

 galvanometric effect was promptly abolished by brief administration of 

 ether or chloroform vapour. Recovery after anaesthesia occurred to 

 some extent — more markedly in the case of ether than in that of 

 chloroform. 



I wish to take this opportunity of thanking Professor Hering for the 

 means of study which I enjoyed at Leipzig, and for his kindness in 

 sparing me much of his own valuable time. 



I would also thank Dr. Waller for kind help and suggestions. 



