THE ENCEPHALON. 429 



always caused motion backwards, or a corresponding attitude. 

 Injuries of one side of it paralysed the same side of the body, 

 as the fibres of the restiform bodies do not decussate like the 

 anterior pyramids. r But Dr. Hertwig asserts that injuries of the 

 cerebellum affect the opposite side, just as Gall found removal 

 of the testis affect the opposite lobe of the cerebellum. Dr. 

 Magendie often found animals perform very regular movements 

 after the removal of the cerebellum ; yet he observed that the 

 removal and wounds of it to a certain depth, and of the chorda 

 oblongata s , gave mammalia and birds a tendency to move back- 

 wards, though the same effect does not occur in fish, which, after 

 the loss of their cerebellum, swim as usual. 



3. In a vertical section of a crus of the cerebellum, or of the 

 mesocephalon from before backwards, the animal immediately 

 rolled forcibly towards the same side, making sometimes sixty 

 revolutions in a minute ; and the corresponding eye was directed 

 forwards and downwards, the other backwards and upwards. After 

 the division of a crus, animals continued rolling, and with their 

 eyes thus directed, for eight days. If both crura were divided, 

 all motion ceased, and the eyes resumed their natural state. l A 

 similar vertical section downwards of the cerebellum from before 

 backwards half way on one side of the central line, through the 

 whole substance of the arch over the fourth ventricle, or of the 

 mesocephalon upwards, had the same effects, and the motion was 

 the more rapid as the section was nearer to the mesocephalon. 

 When an incision of one half of the cerebellum had set an 

 animal rolling to that side, an incision of the opposite crus arrested 

 the rolling and caused the eyes to resume their natural position. 

 A vertical incision downwards in the median line of the cere- 

 bellum caused the animal to attempt motion, but deprived it of 

 the power of balancing itself. Its eyes rolled and started, and its 

 fore legs were rigid and extended forwards. " 



4. If the fourth ventricle is exposed and the cerebellum re- 

 moved, a perpendicular incision in the chorda oblongata on one side 



r Journal de Physique, July, 1823. 



s If ever he amused himself by sticking pins in the chorda oblongata of pigeons, 

 the birds thus ornamented by him would walk and fly backwards for above a 

 month! (Precis, t.i. p. 409.) 



t Journal, t. iv. p. 403. 



u Journal de Physiol. t. iv. All these points were ascertained on noticing the 

 effect of a wound made unintentionally in a crus. 



