288 SPECIAL PHYSIOLOGY. 



Although the will seems unaffected by injury or removal of the 

 cerebellum, the power of executing its various mandates, especially 

 as exhibited in the complicated muscular acts necessary for locomo- 

 tion, is evidently interfered with. If thrown down, an animal from 

 which this organ has been removed, is unable to rise, though it seems 

 to desire to make the effort ; its movements become hurried and irreg- 

 ular, so that there is a want of harmony in its locomotive acts ; its 

 equilibrium is no longer maintained, and it appears as if intoxicated. 

 If a section be made through the middle line of the cerebellum, the 

 power of maintaining the equilibrium is instantly lost, and the animal 

 cannot even stand, but may now turn to one side and then to another. 



When the cerebellum of a bird is gradually cut away, the animal becomes 

 restless, and its movements irregular ; and when the whole organ is thus re- 

 moved, it can no longer walk, leap, or fly, and loses its balance, being unable 

 to perform any acts requiring combination of muscular movements ; yet the 

 reflex movements and sensibility, both appear to remain, as it exhibits no signs 

 of stupor, and endeavors to avoid blows. Laid upon its back, it cannot regain 

 its former attitude, but flutters its wings. When placed on its legs, it stag- 

 gers and falls, as if intoxicated, endeavoring, however, to retain the standing 

 posture. (Flourens.) In other cases, after gradual removal of the cerebellum, 

 a quadruped animal has been noticed to plant all four of its feet firmly on the 

 ground, and then, on further and further portions of the cerebellum being cut 

 away, it moved slowly or quickly backwards. Various other phenomena have 

 been noticed in pigeons mutilated by removal of the greater portion or the 

 whole of the cerebellum ; extension of the legs, with indisposition to flex them, 

 though this could be accomplished by an effort, twisting of the head on the 

 neck, trembling movements of the whole body, vomiting, purgation, and gen- 

 eral emaciation, falling of the feathers, and depression of the natural tempera- 

 ture ; sensation and will were not destroyed. (Wagner.) According to others, 

 the voluntary movements became, after a few days, almost natural, even 

 though two-thirds of the organ had been removed in pigeons. (Hartwig, Dai- 

 ton.) On cutting away portions of one hemisphere of the cerebellum, the most 

 remarkable disturbances in the movements of the animal take place ; for it 

 revolves as if it were on a spit, turning sometimes to one side, and sometimes to 

 the other. If one hemisphere of the cerebellum be entirely removed, by a sec- 

 tion through its peduncles, the animal also revolves in a circle ; this may take 

 place sixty times in a minute, and continue for several days. If the other 

 hemisphere be now cut away, the animal no longer performs these curious move- 

 ments. According to Magendie and Miiller, the rotation is towards the in- 

 jured side, but according to Longet and Lafargue towards the sound side. 

 These differences have been referred to the position and direction of the incis- 

 ions, but the explanation is not quite satisfactory. The cause of the motion 

 is supposed to be due to the one-sided action of the muscles of the body, being 

 no longer counterbalanced by those of the other side ; but another explanation 

 is, that it is caused, not by unbalanced voluntary movements, but by abnormal 

 tonic contractions, excited bv the injury, the spine, especially its anterior por- 

 tion, being twisted, and the animal evidently trying to check the movements. 

 Section of the inferior peduncle of the cerebellum, which connects it with the 

 medulla, causes the animal to bend round to the injured side, from loss of 

 power in the opposite side. Division of the superior peduncles, which pass up 

 to the corpora quadrigemina, whether unilateral or bilateral, has no distinct 

 effect on the movements. 



In a few instances which have been met with in the human subject, 

 of congestion or more serious disease of the cerebellum, such as ex- 

 travasation of blood into one of its peduncles, or pressure from bony 

 or other tumors, backward movements, and continued rotations, have 



