946 INFLUENCE OF THE NERVOUS SYSTEM 



but by another woman of placid temperament, who has reared healthy children 

 of her own. 



951. Other Secretions are in like manner vitiated by mental Emotions, 

 although the influence is not always so manifest. Thus, the halitus from the 

 lungs is sometimes almost instantaneously affected by bad news, so as to pro- 

 duce fetid breath. A copious secretion of fetid gas not unfrequently takes 

 place in the intestinal canal, under the influence of any disturbing emotion ; or 

 the usual fluid secretions from its walls are similarly disordered. The tendency 

 to Defecation which is commonly excited under such circumstances is not, there- 

 fore, due simply to the relaxation of the sphincter ani (as commonly supposed) ; 

 but is partly dependent on the unusually stimulating character of the faeces 

 themselves. The same may be said of the tendency to Micturition, which is 

 experienced under similar conditions ; the change in the character of the urine 

 becoming perceptible enough among many animals, in which it acquires a pow- 

 erfully disagreeable odor under the influence of fear, and thus answers the pur- 

 pose which is effected in others by a peculiar secretion. It is a prevalent, and 

 perhaps not an ill-founded opinion that melancholy and jealousy have a tend- 

 ency to increase the quantity, and to vitiate the quality of the biliary fluid ; 

 perhaps the disorder of the organic function is more commonly the source of the 

 former emotion, than its consequence ; but it is certain that the indulgence 

 of these feelings produces a decidedly morbific effect by disordering the diges- 

 tive processes, and thus reacts upon the nervous system by impairing its healthy 

 nutrition. 



952. The influence of the Nervous System upon those formative processes 

 which constitute the function of Nutrition is less evident than it is upon the 

 Secretory operations ; and the nature of this influence is rather to be inferred 

 from the results of its withdrawal, than to be demonstrated in any more direct 

 manner. These results are chiefly to be seen in the altered nutrition of parts 

 exposed to external impressions, as the integuments generally, but particularly 

 those of the extremities ; and they may be generally expressed by the state- 

 ment, that the withdrawal of nervous influence from a part renders it less able 

 to withstand the destructive influence of physical agencies. It is certain, how- 

 ever, that a great part of the injurious effects which may be observed to follow 

 injuries of the nerves of the extremities experimentally inflicted, are traceable 

 to want of power on the part of the animal, consequent upon the paralyzed 

 state of the limbs, to withdraw them from irritating impressions ( 394, note), 

 and must not be attributed to any direct deterioration of the formative opera- 

 tions, consequent upon the withdrawal of nervous agency. The following case, 

 however, which is given by Mr. Paget 1 on the authority of Mr. Hilton, seems 

 more unequivocally to establish this connection : " A man was at Guy's Hospi- 

 tal, several years ago, who, in consequence of a fracture at the lower end of 

 the radius, repaired by an excessive quantity of new bone, suffered compression 

 of the median nerve. He had ulceration of the thumb, and of the fore and 

 middle fingers, which had resisted various treatment, and was cured only by so 

 binding the wrist that the parts on the palmar aspect being relaxed, the pressure 

 on the nerve was removed. So long as this was done, the ulcers became and re- 

 mained well ; but as soon as the man was allowed to use his hand, the pressure 

 on the nerves was removed, and the ulceration in the parts supplied by it re- 

 turned." Mr. Paget also mentions the following curious case : u A lady, who is 

 subject to attacks of what are called nervous headaches, always finds next morning 

 that some patches of her hair are white, as if powdered with starch. The change is 

 effected in a night; and in a few days after, the hairs gradually regain their dark 

 brownish color." That such effects are rather to be attributed to the loss or 



1 " Lectures on Nutrition," &c., in "Medical Gazette," 1847. 



