CHAP, v.] NUTRITION. 871 



and loss of contractility in muscles which follow upon contusions 

 of nerves as compared with the effects of simple section of nerves ; 

 the occurrence of certain eruptions, such as lichen, zona, ecthyma, 

 &c., in various spinal or cerebral diseases, and indeed the general 

 phenomena, and especially the topography of the eruption, of a 

 large number of cutaneous diseases. Lastly but not least we 

 might quote the general process of inflammation. These are 

 examples of disordered nutrition. To them we might add as 

 instances of altered but yet orderly nutrition the remarkable 

 connections observed between changes in the form of the fingers 

 and growth of the nails and hairs, and certain internal maladies, 

 such for instance as the ' clubbed fingers ' of phthisical and other 

 patients, and the like. We might also call attention to the 

 influence of light on the nutrition of animals. The experience of 

 blind people and blind animals indicates some special connection 

 between visual sensations and the nutrition of the skin ; and this 

 can hardly be other than a nervous connection. The effects of 

 prolonged darkness on nutrition in general and the experimental 

 results which shew that the total metabolism of the body is 

 influenced by light, also suggest some nervous action. The in- 

 fluence of cold again in determining the growth of hair points in 

 the same direction. 



Making every allowance for the intervention as factors in the 

 production of the phenomena quoted above of such common 

 actions of the nervous system as are already well known to us, 

 such as vaso-motor changes, making every allowance for the con- 

 sequences of the failure or bluntness of sensation and the absence 

 of those beneficial after results of muscular activity which we 

 pointed out in 86, recognizing moreover that changes in one 

 organ may affect the condition of other distant organs by changes 

 induced in the composition or qualities of the blood, there still 

 remains a residue which seems distinctly to point to the con- 

 clusion that the influence of the nervous system is not limited to 

 such changes of the muscles as belong to the production of con- 

 tractions or the generation of heat, but bears on the whole 

 nutrition of the muscle ; and we shall meet with further evidence 

 in this direction when we come to deal with the central nervous 

 system. Similar considerations lead us also to conclude that the 

 influence of the nervous system bears on the whole nutrition of 

 the glands, of the blood vessels, of the skin and the connective 

 tissues in general, in fact of nearly the whole body. 



Such an influence of the nervous system has often been spoken 

 of as 'trophic'; and the term has often been used as if the growth 

 and nourishment of a tissue were the result of nervous action, or 

 at all events could not be complete without the intervention of 

 nervous impulses. Hence, in this view, the consequences following 

 upon section of the fifth nerve are regarded as due to the falling 

 away of ' trophic ' influences. Such a view has however no sound 



