694 THE LIFE AND WORKS OF BKOWN-SEQUARD. 



rhages in distant organs, or, indeed, cedemas and anaemias; it may 

 even disturb or increase the nutrition of those organs; suspend or 

 exaggerate their secretions. These effects may also be produced either 

 on the opposite side from the injured or irritated nerve or on the same 

 side. Conversely, the lesion or irritation of a principal nerve may 

 produce, either at once or after a considerable time, disorders in the 

 encephalic centers. For example, a section of the sciatic nerve in- 

 creases the irritability of one-half of the nervous system and decreases 

 that of the other half. In this kind of phenomena it may be that the 

 same symptom may result from a lesion of different organs. And, 

 inversely, the real efficient cause, the pathological primum movens can 

 not be ascertained without a delicate and complete analysis of the 

 phenomena. It may be remarked here that the excitability of the 

 sensory or motor nerves that serve as intermediaries for such effects 

 is independent of their special aptitude for the conduction of sensory 

 impressions or motor impulses. 



The assembling and interpretation of these phenomena constitute a 

 special branch of physiology developed by Brown-Sequard, and com- 

 prised under the names dyuamogeny and inhibition. It is an entirely 

 new doctrine, which he opposed to that of cerebral localization. It 

 concerns not only physiology but psychology itself; that is to say, the 

 domain of conduct and intelligence which has its seat in the brain. 

 These are indeed verities of fact independent of auy metaphysical 

 theory. Yet, we hasten to add, the conclusions of Brown-Sequard 

 were too absolute. If the facts that he cited did not seem doubtful, 

 he at least exaggerated them by a too wide generalization. He had, 

 however, none the less, the merit of having stated this problem and 

 shown its full extent. 



There are few phenomena in which inhibition exerts a more striking 

 influence than in those which result from the action of the vasomotor 

 nerves. As early as 1851 Claude Bernard had observed the local rUes 

 of temperature and increased activity of the circulation that follows a 

 section of the cervical sympathetic nerve. Conversely, Brown dis- 

 covered that a stimulation of that nerve contracts the same vessels 

 that its section dilates and reduces the temperature of that region 

 which shows a rise when the nerve is cut. By an analogous correla- 

 tion, if we plunge one hand in water, a thermometer placed in tl e 

 other hand shows a decrease in temperature. 



The development of these ideas may be carried still further, and 

 thus Brown was led to the most remarkable discoveries, for instance, 

 to the experimental production of epilepsy and the hereditary trans- 

 missions of lesions by whose aid he was able to produce that malady. 

 His experiments went back, indeed, to 1852-5.3. They were the imme- 

 diate result of his investigations upon inhibition, and he carried tbem 

 on for a quarter of a century. He operated preferably on guinea pigs, 

 animals possessed of considerable vitality and easily propagated. He 



