Page:Popular Science Monthly Volume 44.djvu/354

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THE relation that exists between the activity of the nervous system and resistance to causes of destruction may be illustrated by facts of different sorts. It has been often remarked, and the registers of the academies confirm it, that we find many old men among scientific and literary people. Whether the resistance in question is attributable to the habitual exercise of the mental functions, or vital resistance and mental power are conjointly attributable to a good natural organization, the relation is no less certain. The same relation is found, susceptible of like interpretations, among persons without cultivation, whose existence has been, as we might say, all organic, and who are more exposed to the action of atmospheric inclemencies and to all the chances of mortality. The remark is attributed to Baillon by Cabanis that porters and laboring men offer only a feeble resistance to blood-letting and purgatives. Nothing is more remarkable than the facility with which weak-minded persons succumb to acute diseases of every kind.

Many violent maladies have been supposed to have been produced under the operation of moral influences. Sennert believed that fear was capable of provoking erysipelas, Hoffmann also made fear and the adynamy resulting from it play an important part as the predisposing cause of contagious diseases. Dr. H. Tuke believed, in particular, in the influence of fear upon the contagion of rabies. The breaking out of rabies has been sometimes observed after psychic emotion. Bouley cites the case of a dog which went mad after having been immersed in water. Gamléia cites a similar case in a man, and another in a woman who was frightened by a drunken man. In order to avoid the influence of fear, Desgenettes concealed the name and the nature of the plague; and it is to be remarked further that the Turks died less rapidly of it than the Christians. Cullen supposed that sad emotions favor contagious diseases, and particularly the plague. This disposition to contagion after violent emotions which determine discharge of the secretions may be partly explained by the fact that the conditions that diminish the proportion of the liquids of the blood favor absorption. It, however, seems at least probable that the nervous discharge is accompanied by alterations of the blood and modifications of the interior medium which justify the popular expressions concerning having bad blood and turning the blood. It is admitted that