872 INFLUENCE OF THE NERVOUS SYSTEM 



affection is often limited to certain nerve regions, and that post-mortem ex- 

 amination has shown that the nerves in question are swollen and affected 

 with hypertrophy of the interstitial connective tissue. And as the cutaneous 

 affection commences with anaesthesia, it seems probable that the nerves are 

 primarily affected. Then again there are the remarkable phenomena ob- 

 served and described by Suellen, Schiff, and many others, 1 which follow iu- 

 tracranial section of the fifth pair of nerves, and which consist in the occur- 

 rence of conjunctivitis within a few hours of the operation, the discharge of 

 a thick puriform mucus, haziness, ulceration, and ultimately sloughing of 

 the cornea, and the loss of the eye on the same side as that on which the 

 nerve has been divided. Lastly, there are the atrophic changes which occur 

 in muscles when a motor nerve is divided, and which have been described 

 with great minuteness by M. Vulpiau, 2 by Erb, and others, the fibres losing 

 their transverse strue, and gradually undergoing fatty degeneration, whilst 

 the nuclei of the sarcolemma and the interstitial connective tissue undergo 

 hypertrophy. Thus it would at first sight appear there is a large amount of 

 evidence proving the direct influence of the nervous system on the processes 

 of nutrition. 



719. It is not less certain, however, that weighty evidence can be adduced 

 to show that the nervous system is not required for the due performance of 

 the nutritive processes, and has little or no direct action upon them, the 

 pathological phenomena above mentioned as concurrent with their persistent 

 irritation, or consequent on their paralysis, resulting from changes in the 

 supply of blood, which again are caused by the action of the vaso-motor 

 nerves upon the vessels. In proof of this it may be observed, in the first 

 place, that nutrition and the processes which minister to it, as absorption, 

 assimilation, circulation, secretion, the fixation of new material, and the dis- 

 integration and removal of the old, are all actively performed by plants, 

 though there is no evidence of the existence of such a rudimentary nervous 

 system in the vegetable kingdom. Again, in many of the lower forms of 

 animal life, as well as in the more lowly organized tissues of the higher ani- 

 mals, such as cartilage, fat, and connective tissue, few or no nerves are pres- 

 ent, and nervous influence, if perceptible at all upon the process of nutrition 

 in them, must therefore be indirect. Thirdly, daily experience shows that 

 even in the higher animals, sensory nerves may be divided without any iail- 

 ure in the processes of nutrition of the parts they supplied. 3 In regard to 

 motor nerves, the experiments of Reid made long ago showed clearly that 

 although atrophy of muscle follows section if the limb be allowed to remain 

 quiescent, yet that the muscles retain all their characters if they are me- 

 thodically exercised by passive movement, or by the action of the electrical 

 current. Brown-Sequard records cases where mixed nerves 4 have been di- 

 vided without apparent alteration being produced either in the temperature 

 or in the nutrition of the parts beyond. Lastly, even with regard to the 

 sympathetic there is evidence that section of its trunk on one side in the 

 neck, if anything, improves rather than deteriorates nutrition on the same 

 side of the head, for the vaso-motor system being paralyzed, the current of 

 blood becomes freer, causing the hair on that side to grow more rapidly in 

 tlio mammal, and the lateral half of the comb of the cock to hypertrophy, 

 whilst injuries heal more rapidly, and the tissues, as in the case of the cornea 



1 See especially Sinitzin, Centralblatt fur die Mod. Wiss., 1871, p. 100. 

 1 Brown-Se'quard's Archives, 1H7-, p. 7"> : S. 



3 Sec ease, ly Vaii/.etti (Brown-Se.pianl's Archives, 1872, p. 152), in which the 

 lingual ncrvo was resected on one side, and in three months after the organ still pre- 

 served its normal form, color, and nutrition. 



4 Archives, 1869. 





