202 On -Trophic Nerves. [April, 



recognized by the laity, even at times when the faculty inverted the 

 relations of effect and cause which really do exist between many 

 manifestations of mal-nutrition, such as dyspepsia and cystitis, on 

 the one side, and cerebral overwork and spinal exhaustion on the 

 other. It is to Dr. Gull* that we owe a demonstration of the facts 

 that the painful affections specified, as well as others only alluded 

 to, are antecedents, but in the sense in which a man's shadow ante- 

 cedes him when the sun is at his .back ; that the doctrine of reflex 

 paraplegia was wrongly applied to those cases ; and that they are 

 really to be explained as being of the same character as those fur- 

 nished to us in the histories of men subjected, in prison, as if in an 

 experiment, to the working of mental depression. 



Simpler cases still are furnished to us by the well-authenticated 

 accounts of persons losing all their hair after cerebral injury .f 

 When we consider how large an organ the brain is relatively to the 

 rest of the body, and how, protected as it is by its lodgment within 

 an air-tight cavity, it can say to all other organs of the body, 

 " Thou shalt want before I shall," there is no need to waste time 

 in imagining how its derangement may and must entail derangement 

 throughout the entire body. It may be profitable -to discover by 

 investigation how this secondary derangement is brought about, 

 whether indirectly by vasomotor alteration, or directly by molecular 

 disturbance set up intracellularly. At present the necessary inves- 

 tigations have not been set on foot; and, ad interim, we may 

 colligate the facts under Mr. Darwin's expression of " correlation of 

 growth." 



We come in the third place to cases of greater simplicity still ; 

 and by this we do appear at first sight to be brought within the 

 sphere of the explanation which the phrase " Trophic nerves " im- 

 plies. These cases are constituted by the accidental severances of 

 nerves which take place in civil, and more especially in military life, 

 the musculo-spiral nerve, whence the greater part of the thumb and 

 lesser proportions of the three fingers next to it receive their dorsal 

 supply, being specially well fitted for such experimentation, and 

 specially obnoxious to it in the " pious pastime " of war. Dr. S. 

 Weir Mitchell has put on record, in ' The Contributions relating to 

 the Causation and Prevention of Disease, and to Camp Diseases,' 

 edited by Dr. Austin Flint, and published by the United States' 

 Sanitary Commission, some very valuable observations as to the 

 effects of such injuries to nerves. These we find summed up as 

 follows by a writer in the ' Edinburgh Monthly Medical Journal ' for 

 January, 1869, at pp. 646, 647 :— 



" There is a careful and interesting description of glossy skin 



* See ' Guy's Hospital Reports,' iii., 7 : 1861. 



t See 'Lancet,' July 10, 1869: and 'Holmes' System of Surgery,' i., article 

 " Accidents from Lightning." p. 750. 



