350 PHYSIOLOGY 



they may be developed normally even in the complete absence of a central 

 nervous system. Whether we are justified in assuming the existence of 

 trophic nerves exercising an influence on the nutrition of the part they supply, 

 apart from any influence on its other functions, the experimental evidence 

 before us is not sufficient to decide ; nor can we as yet give a physiological 

 analysis of the changes in nutrition which may be brought about in hysterical 

 patients under the influence of emotion. 



