Mr. H. F. Baxter on Nerve Force, 13 



marked decrease in the nerve current ; and the effect, the oscilla- 

 tion of the needle, was evidently due to the motion produced in 

 the nerve by the muscular contractions. Instead of exciting the 

 spinal extremity of the nerve, the sole of the foot was irritated 

 by pieces of glass so as to cause reflex actions ; the effects were 

 the same. 



In other experiments the distal extremity of the sciatic nerve 

 was divided, and the electrode, instead of being inserted into the 

 nerve, was placed in contact with the divided surface, the other 

 electrode being placed upon the external or longitudinal surface; 

 there was not the same oscillation of the needle as before, 

 neither was there any marked or sudden decrease ; the needle 

 gradually receded. 



The nerve, and sometimes the spinal cord, was irritated by 

 other means (chemical* and mechanical) so as to produce con- 

 tractions ; but the results were the same. It need scarcely be 

 stated that, when employing these means to excite muscular 

 contractions, great care is requisite that the chemical reagents, 

 or the electrodes of the battery, should not come into contact with 

 the electrodes of the galvanometer, and that the mechanical agent 

 should not consist of steel or iron, so as to act upon the needle of 

 the galvanometer. In short, in all these and similar experiments 

 where the galvanometer is employed, no steel should be about 

 the person, such as covered metallic buttons in the sleeves of the 

 coat, or penknives in the pockets ; nor should the shade of the 

 galvanometer be exposed to the heating effect of the sun's rays. 



Before quitting this part of my subject, I may just allude to 

 the question respecting an increase in the nerve current during 

 nerve action ; but having considered it on a former occasion, I 

 need do no more than refer to my published paper f containing 

 an account of the experiments in which I failed to obtain any 

 decided evidence of an increase in the nerve current during nerve 

 action. 



From the results obtained in the foregoing experiments, I can 

 come to no other conclusions than the following : — - 



1st. That no sudden or marked decrease in the electric condi- 

 tion of the nerve occurs during nerve action. 



2ndly. That the decrease which is observed arises from a dis- 

 organization of the nerve. 



3rdly. That there is no evidence of a conversion of the electric 

 force of the tissue into nerve force during nerve action. 



* In a Report on Muscular Contraction, by A. B. Duffin, M.D., pub- 

 lished in Professor Beale's 'Archives of Medicine ' for January 1862, will be 

 found some valuable results obtained by Kuhne, respecting the action of 

 the different chemical reagents upon nerves and upon muscles. 



t hoc. cit. 



