CHAP, v.] NUTRITION. 471 



nervous guidance its nutrition becomes profoundly affected. We 

 are not justified in saying that in this case the nutrition of the 

 salivary cell is directly dependent on the nervous system, because 

 all biological studies teach us that the growth, repair, and repro- 

 duction of protoplasm may go on quite independently of any 

 nervous system, and the nutrition of the nervous system itself 

 cannot be dependent on the action of that system on itself; but 

 we may go so far as to infer that the nutrition of the salivary cell 

 is in the complex animal body so arranged to meet the constantly 

 recurring influences brought to bear on it by the nervous system, 

 that, when those influences are permanently withdrawn, it is thrown 

 out of equilibrium ; its molecular processes, so to speak, run loose, 

 since the bit has been removed from their mouths. And we might 

 expect that similar instances would be met with where nutrition 

 became abnormal after the removal of wonted nervous influences. 

 Such instances indeed are not uncommon. And there are many 

 pathological phenomena, inflammation itself to begin with, which 

 seem inexplicable, except when regarded as the result of nervous 

 action. As examples we might mention the rapid and peculiar 

 degeneration of and loss of contractility in the skeletal muscles in 

 certain affections of the spinal cord, the changes in the muscles 

 being more rapid and profound than in the nerves; the pheno- 

 mena of bed-sores, especially the so-called acute bed-sores of 

 cerebral apoplexy ; some at least of the cases of vesical affections 

 attendant on spinal or cerebral diseases or injuries ; the more 

 rapid atrophy 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, 

 frequently accompanied, as in maladies affecting the posterior 

 cornua, with intermittent pains ; and indeed the general phe- 

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

 large number of cutaneous diseases. In all these cases, however, 

 there are many attendant circumstances to be considered before 

 we can feel justified in speaking of any direct influence of the 

 nervous system on nutrition, of any specific action of what have 

 been called 'trophic' nerves. Perhaps the instance which has 

 been best worked out is the connection of the nutrition of the eye 

 and face with the fifth or trigeminal nerve. When in a rabbit the 

 trigeminus is divided in the skull there is loss of sensation in those 

 parts of the face of which it is the sensory nerve. Very soon, 

 within twenty-four hours, the cornea becomes cloudy ; and this is 

 the precursor of an inflammation which may involve the whole eye 

 and end in its total disorganization. At the same time the nasal 

 chambers of the same side are inflamed, and very frequently ulcers 

 make their appearance on the lips and gums. Seeing how delicate 

 a structure the eye is, and how carefully it is protected by the 



