414: NEKVOUS SYSTEM. 



or enfeeblement of certain muscles upon one side of the 

 body, to a direct or reflex irritation of the parts of the 

 nervous system involved, or to all of these causes combined. 

 The experiments of Brown-Sequard and others conclusively 

 show that the movements may be due to irritation alone, for 

 they occur when parts of the encephalon and the upper por- 

 tions of the cord are simply pricked, without section of fibres. 1 

 When there is extensive division of fibres, it is probable that 

 the effects of the enfeeblement of certain muscles are added to 

 the phenomena produced by simple irritation. The most 

 satisfactory explanation of these movements is the one pro- 

 posed by Brown-Sequard, who attributes them to a more or 

 less convulsive action of muscles on one side of the body, 

 produced by irritation of the nerve-centres. He regards the 

 rolling as simply an exaggeration of the turning movements, 

 and places both in the same category. 3 It is proper to state, 

 however, that this explanation is not accepted by Longet 3 or 

 by Vulpian, 4 both of whom have made numerous experiments 

 with regard to the movements of rotation. In addition to 

 the phenomena just described, Magendie has noted remark- 

 able movements of the eyes following section of one of 

 the peduncles of the cerebellum. " The eye of the side op- 

 erated upon is directed downward and forward : that of the 

 opposite side is fixed in a direction upward and backward, 

 which gives to the face a curious expression." 5 Longet 

 noted the same phenomena in dogs and rabbits after division 

 of one of the restiform bodies. 6 



1 BROWN-SEQUARD, On Turning and Rolling produced by Injuries of the 

 Nervous System. Experimental Researches applied to Physiology and Pathology, 

 New York, 1853, p. 21. 



2 BROWN-SEQUARD, Note sur les mouvements rotatoires. Journal de la physi- 

 ologie, Paris, 1860, tome Hi., p. 720. 



3 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 397, ft seq. 



4 VULPIAN, Systeme nerveux, Paris, 1866, p. 594. 



5 MAGENDIE, Lecons sur les fonctions et les maladies du systeme nerveux, Paris, 

 1841, tome i., p. 261. 



6 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 392. 



