THE FUNCTION OF THE CEREBELLUM 715 



for the coordination of voluntary movements, while Rolando (1809), 

 Weir Mitchell (1869), and Luciani considered it as an organ for the 

 reinforcement of the activity of the musculomotor centers of the 

 cerebrum and spinal cord. Munk ascribed to it the function of 

 preserving the equilibrium of the body, while Hitzig saw in it the 

 association center of the muscle sense. The last view has been 

 advocated more recently by Lewandowsky 1 and Sherrington. 



In last analysis we are dealing here with a reflex or excitomotor 

 function of the cerebellum, in consequence of which the musculature 

 of our body is forced to act within perfectly definite channels. We 

 obtain an absolutely set condition of tonus, a certain amplitude of 

 contraction, and a coordination of the activities of the different muscles. 

 Thus, the only factor to be determined as yet is the intrinsic stimulus 

 which causes the cerebellum to discharge these regulatory impulses. 

 In the nature of this process, the latter may be either acceleratory 

 or inhibitory. 



In accordance with the view of Lussana, Hitzig and Lewandowsky, 

 the cerebellum is to be regarded as the center for the muscle-sense, 

 in which the different centripetal impulses from these sense organs 

 are associated to give rise to coordinated motion. This association, 

 however, does not involve consciousness, as does the association 

 taking place in the cerebral centers, but remains subconscious, or 

 more correctly speaking, reflex in its nature. Sherrington has gone 

 a step farther and designates this organ as the head ganglion of 

 the proprioceptive system, in which the different impulses from the 

 muscle-spindles and from the labyrinth are brought together and asso- 

 ciated subconsciously. From here the resulting impulses are conveyed 

 through the superior peduncle into the cerebrum, where they influence 

 the function of the motor areas. Other impulses are made to travel 

 outward by way of its connections with the pons and bulb, and to 

 direct the activity of the distant musculature. In this way, a com- 

 plex mechanism is established which is concerned with the coordina- 

 tion of the musculature in general, but more particularly with that 

 having to do with the maintenance of the equilibrium of the body 

 as its position in space is changed to suit particular purposes. 



1 Archiv fur Physiol., 1903, 129. 



