THE NERVOUS SYSTEM. 91 



would permit any person to press upon the exterior of this organ, 

 when he would suddenly fall down, as in a fit ; as soon as the pres- 

 sure was removed, recovery immediately followed. Whether sen- 

 sation as well as motion was thus suspended is not stated. 



M. Majendie has made some curious discoveries connected with 

 the effects of lesion of the parts situated above the medulla ob- 

 longata. When parts situated in the ventricles (corpora striata) are 

 cut, the animal immediately darts forward and runs with rapidity. 

 This phenomenon, he says, is particularly remarkable in young 

 rabbits, the animal appearing to be impelled forward by a power 

 within, which it cannot resist. It is a curious fact connected with 

 this observation, that horses are subject to a disease that produces 

 similar effects. The diseased animal easily goes forward, and will 

 even trot or gallop quickly, but seems incapable of going back- 

 wards, and appears to have difficulty in arresting its progressive 

 motion. On the other hand, when the cerebellum or medulla ob- 

 longata was injured in a certain manner, the tendency always was 

 to move backwards. Some pigeons which had been thus injured 

 constantly moved backwards in walking for more than a month, 

 and even flew backwards when thrown into the air. Another sin- 

 gular movement took place when the parts leading from the spinal 

 cord up to the cerebellum (crura cerebelli) were cut. When the 

 one on the right is cut, a whirling motion takes place on that side, 

 and sometimes with such rapidity that sixty turns are made in a 

 minute. M. Majendie says he has seen this continue for eight 

 days, without stopping, to speak properly, for a single instant. 

 When the opposite crus cerebelli is cut, rotation takes place on the 

 opposite side ; and when both are cut, motion in both directions 

 ceases. Probably some disease of these parts existed in an insane 

 person who was some years ago confined in one of the Edinburgh 

 asylums, and who incessantly occupied himself in turning round in 

 one direction. He might be stopped, or forced to turn in an oppo- 

 site direction, but when left to himself, immediately turned as 

 before. 



We are indebted to Sir Charles Bell, however, for perhaps the 

 most brilliant discovery ever made connected with the functions of 

 the nervous system. We refer to his discovery of the different 

 parts upon which motion and sensation depend. This distinguished 

 physiologist was led to his investigations partly from considering 

 the distribution of certain nerves, and partly from cases in which a 

 person wholly loses the power to move a part of the body, and yet 



