AS TO THE STRUCTURE AND FUNCTIONS OF NERVE 319 



grey matter has been much disputed, but the recent I'esearches of 

 Wagner, Bidder, Kupfer, and Ovvsjannikow, throw a great hght upon, 

 and vastly simpHfy the whole problem. It would appear that all 

 nerve fibres are processes of ganglionic corpuscles ; that, in the spinal 

 cord, the great mass of the grey matter is nothing but connective 

 tissue, the true ganglionic corpuscles being comparatively few, and 

 situated in the anterior horns of the grey substance ; finally, it would 

 seem that no ganglionic corpuscle 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 connection 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 pheno- 

 mena exhibited by active nerve were 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 Fullerian course) 

 which prove that the transmission of a constant current 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 



