436 Prof. Huxley^ on the Structure, ^c. of Nerve. [May 15, 



corpuscles ; that, in the spinal cord, the great mass of the grey 

 matter is nothing but connective tissue, the true ganglionic corpus- 

 cles being comparatively few, and situated in the anterior horns of 

 the grey substance ; finally, it would seem that no ganglionic cor- 

 puscle has more than five processes ; one, which becomes a sensory 

 fibre and enters the posterior roots of the nerves ; one, a motor 

 fibre which enters the anterior roots ; one, which passes upward to 

 the brain ; one, which crosses over to a ganglionic corpuscle in the 

 other half of the cord ; and perhaps one establishing a connexion 

 with a ganglionic corpuscle on the same side. 



It is impossible to overrate the value of these discoveries ; for if 

 they are truths, the problem of nervous action is limited to these 

 inquiries : (a) What are the properties of ganglionic corpuscles? 

 {b) What are the properties of their two, or three, commissural 

 processes? For we are already pretty well acquainted with the 

 properties of the sensory and motor processes. 



A short account was next given of the physical and physiological 

 phenomena exhibited by active and inactive nerve ; and the phe- 

 nomena exhibited by active nerve w^ere shown to be so peculiar as 

 to justify the application of the title of " nerve force " to this form 

 of material energy. 



It was next pointed out that this force must be regarded as of 

 the same order with other physical forces. The beautiful methods by 

 which Helmholtz has determined the velocity (not more than about 

 80 feet in a second in the frog), with which the nervous force is 

 propagated were explained. It was shown that nerve force is not 

 electricity, but two important facts were cited to prove that the 

 nerve force is a correlate of electricity, in the same sense as heat 

 and magnetism are said to be correlates of that force. These facts 

 were, firstly, the " negative deflection " of Du Bois Raymond, 

 which demonstrates that the activity of nerve affects the electrical 

 relations of its particles ; and secondly, the remarkable experiments 

 of Eckhard (some of which the speaker had exhibited in his Ful- 

 lerian course) which prove that the transmission of a constant 

 currrent along a portion of a motor nerve so alters the molecular 

 state of that nerve as to render it incapable of exciting contraction 

 when irritated. 



These facts, even without those equally important though less 

 thoroughly understood experiments of Ludwig and Bernard, which 

 appear to indicate a direct relation between nerve force and 

 chemical change, seem sufficient to prove that nerve force must 

 henceforward take its place among the other physical forces. 



This then is the present state of our knowledge of the structure 

 and functions of nerve. We have reason to believe in the existence 

 of a nervous force, which is as much the property of nerve as mag- 

 netism is of certain ores of iron ; the velocity of that force is 

 measured ; its laws are, to a certain extent, elucidated ; the struc- 

 ture of the apparatus through which it works promises soon to be 



