Mr. H. F. Baxter on Nerve Force. 17 



placed on the surface of the convolution ; the effect upon the 

 needle amounted to 3°. There was no difference in this respect 

 whether the experiment was made on the convolutions of the 

 cerebrum or those of the cerebellum. The greatest care, how- 

 ever, is required not to allow one of the electrodes to come into 

 contact with the blood from a wounded vessel, as the effect upon 

 the needle was then very decided, amounting to 10° or 15° or 

 more. Here, then, in these experiments we obtained the same 

 effects (the nerve current) as with the two surfaces of a nerve, 

 and, what is more to the purpose, the amount is not greater than 

 with a nerve. 



It was impossible to perform similar experiments with the 

 grey matter of the spinal cord, inasmuch as the two surfaces are 

 divided sections. When, however, one electrode was placed on 

 the longitudinal surface of the cord, and the other in contact 

 with the divided surface, no difference was observed when the 

 latter electrode was placed in contact with the grey matter or 

 with the white matter of the cord; the longitudinal surface was 

 positive to the other as with a nerve. 



Similar experiments were made on the cervical ganglia of 

 rabbits and guinea-pigs, by placing the electrodes one on the 

 surface, and the other in contact with the divided surface; the 

 effect upon the needle amounted to 2° or 3°. 



In all these experiments I could obtain no evidence to lead to 

 the supposition that the electric condition of the vesicular or 

 ganglionic portion of the nervous system differed from that of 

 the white or fibrous, or that the intensity of the nerve current 

 was such as to lead to the conclusion that the nutritive actions 

 were more active in the ganglionic than in the white portion. 



It may be said that the foregoing experiments do not show or 

 prove that the vesicular or ganglionic portion is not the source 

 of nervous power, but only that nerve force is not generated like 

 galvanic force. I grant these objections, and am willing to allow 

 them their full force; but they prove this fact, that there is not 

 that difference between the two portions of nervous matter to lead 

 us to suppose that they are endowed with distinct properties. 



§ IV. Concluding Remarks. 



Let us now consider the grounds upon which it is believed 

 that nerve force is generated in the central parts (the ganglionic) 

 of the nervous system ; the evidence will resolve itself into this : 

 if from any cause the influence of the will be not transmitted to 

 the limb so as to cause contractions, it is tacitly assumed that 

 this arises from the non-transmission of nerve force to the part, 

 and consequently that there must be some part in which this 

 force is generated, prior to its being transmitted. I will not say 



Phil. Mag. S. 4. Vol. 24. No. 158. July 1862. C 



