FUNCTIONS OF THE CEREBELLUM. 323 



ry character is displayed, so the same holds good for the hemispheres, 

 their relations with the spinal cord through the restiform bodies being 

 also of a sensory nature. It seems probable that the superficial vesicu- 

 lar material is in anatomical connection with the thalamus, and the cor- 

 pus dentatum or inner ganglia with the posterior or sensory columns of 

 the cord. 



The arguments which have been brought forward by those who sup- 

 pose the cerebellum to have for its office the co-ordination of The doctrine 

 general muscular movement, may be briefly quoted as fol- 

 lows : There appears to be a general correspondence between motion, 

 its size and the degree of energy and complication of the motor powers 

 in various animals. Thus, in fishes, and likewise in birds, those tribes 

 which excel in their powers of motion, or are distinguished by the com- 

 plication of their movements, are characterized by the manner in which 

 this organ is developed ; and the same may be said even of the mamma- 

 lia, quadrupeds whose locomotive mechanism is simple possessing it in 

 a lower state of development than those which either temporarily or 

 constantly move on the posterior extremities. Among apes, those which 

 more frequently assume the erect posture, which is normal to man, have 

 their cerebellum of a size more closely approaching to his. 



On examining such facts, it appears that it is not so much muscular 

 power as the quality of co-ordinating and governing minute muscular 

 motions. To maintain the standing position motionless, there are, in re- 

 ality, a great many muscular movements required, which serve to antag- 

 onize all the little incidents producing a tendency to fall ; and if this be 

 so in standing, how much more difficult must such antagonizing and 

 compensating actions become in walking, running, and such movements. 

 Theoretically, it might be expected that some special organ is necessary 

 to combine such various actions, and that organ seems to be the cere- 

 bellum. 



In confirmation of this are the experimental results which have been 

 obtained. The cerebellum, on irritation, gives rise to no Results of ex- 

 convulsive motions, nor to sensations. If removed by de- ft"corebei^ 

 grees in successive slices, the motions of the animal become lum. 

 irregular, and, finally, it loses all power of walking or of maintaining its 

 equilibrium. Though the powers of the animal in bringing its muscles 

 into contraction seem not to have suffered, it can not co-ordinate or com- 

 bine the necessary muscular exertions, and, as is graphically stated, stag- 

 gers and falls over like a drunken man, still making efforts to maintain 

 its balance. Such experiments have been repeatedly made in the case of 

 different animals, and with the same results. 



Connected with these results of experimental lesions of the cerebellum 

 are the rotations, as they are termed, which occur, for example, when one 



