BEOWN-SEQtTARD ON THE CENTRAL NEEYOUS SYSTEM. 2S3 



behind what relates to voluntary movements and sensibility, we come 

 to the consideration of the influence of the nervous system on nutri- 

 tion, animal heat, secretion, &c. ; and, first, of the physiological and 

 morbid actions due to the great sympathetic nerve. 



There is perhaps no department of physiology in which, within a 

 recent period, two or three discoveries have afforded so comprehensive 

 an elucidation of a large number of comparatively isolated facts, as in 

 that connected with the vaso-motor nervous system. It was probably 

 for the want of these discoveries that the observations of the thought- 

 ful "Why tt and of the profound Prochaska, were so long neglected and 

 apparently forgotten, or, at all events, that their real importance was by 

 no means understood. The expression of Prochaska with reference to 

 the capability of sensorial, being reflected into motor impressions, suf- 

 ficiently proves that the mind of this great physiologist had grasped 

 the idea which Le Grallois and Mayo, Marshall Hall and Miiller "did 

 so much to develop subsequently. But even the facts accumulated 

 by the latter observers hung together but loosely, until their connexion 

 and value were indicated by the more recent researches of Claude 

 Bernard, Brown- Sequard, and others. 



Professor Claude Bernard published the results of his first re- 

 searches on the effects of division of the cervical sympathetic nerve, 

 in 1851 and the beginning of 1852. The great fact announced in 

 these publications was, that this section was constantly followed by 

 a considerable afflux of blood to the parts of the head supplied by 

 the sympathetic. Along with the greater afflux of blood and accom- 

 panying dilatation of the blood-vessels, the temperature becomes 

 elevated, hyperesthesia is noticed, and the vital properties of the 

 parts generally become increased. 



Dr. Brown- Sequard, with Dr. Tholozan, had before this, performed 

 an experiment which, taken in connexion with the preceding, prepared 

 the way for what was to be expected from galvanisation of the cervical 

 sympathetic, after sections of it had first given rise to the above pheno- 

 mena. The experiment alluded to is one of prime and fundamental im- 

 portance, and was undertaken with the intention of trying whether Dr. 

 W. P. Edwards was right in his assertion, that if the temperature of 

 one part of the body be raised or lowered, a corresponding rise or fall 

 takes place, more or less, in all other parts of the body, according 

 to circumstances. This assertion is found quite true in one sense, 

 yet in exactness to bear an interpretation quite different from that 

 put upon it by Edwards. 



Drs. Brown-Sequard and Tholozan^ found that if one hand was 

 plunged in water at tne temperature of its freezing point, a very strong 

 lowering action was exercised on the temperature of the other hand, 

 while a thermometer placed in the mouth indicated but slight diminu- 

 tion of heat : thus, in one case, the hand kept in the atmosphere lost, in 

 seven minutes, 22° Pahrenheit, while the temperature of the mouth was 

 not diminished more than the fifth of a degree. We therefore cannot 

 hesitate to admit that this cooling of the hand in the atmosphere was 



