648 HANDBOOK OF PHYSIOLOGY. 



want of harmony of muscular movements were the consequence of remov- 

 ing the superficial layers. When he reached the middle layers, the ani- 

 mals became restless without being convulsed; their movements were 

 violent and irregular, but their sight and hearing were perfect. By the 

 time that the last portion of the organ was cut away, the animals had 

 entirely lost the powers of springing, flying, walking, standing, and 

 preserving their equilibrium. When an animal in tins state was laid upon 

 its back, it could not recover its former posture, but it fluttered its 

 wings, and did not lie in a state of stupor ; it saw the blow that threatened 

 it, and endeavored to avoid it. Volition and sensation, therefore, were 

 not lost, but merely the faculty of combining the actions of the muscles; 

 and the endeavors of the animal to maintain its balance were like those 

 of a drunken man. 



The experiments afforded the same results when repeated on all classes 

 of animals; and from them and the others before referred to, Flourens 

 inferred that the cerebellum belongs neither to the sensory nor the intel- 

 lectual apparatus; and that it is not the source of voluntary movements, 

 although it belongs to the motor apparatus; but is the organ for the co- 

 ordination of the voluntary movements, or for the excitement of the com- 

 bined action of muscles. 



Such evidence as can be obtained from cases of disease of this organ 

 confirms the view taken by Flourens: and, on the whole, it gains sup- 

 port from comparative anatomy; animals whose natural movements 

 require most frequent and exact combinations of muscular actions being 

 those whose cerebella are most developed in proportion to the spinal 

 cord. 



We must remember, too, that the cerebellum is connected with the 

 posterior columns of the cord as well as with the direct cerebellar tract, 

 both of which probably convey to the middle lobe muscular sensations. 

 It is also connected with the auditory nerves and bulb by the internal and 

 external acute fibres; and with the tegmentum through the red nuclei. 

 Its connection with the efferent tracts from the different cerebral lobes 

 through the pons is also highly important. Movements of the eyes also 

 occur on direct stimulation of the middle lobe. It seems, therefore, to 

 be connected in some way with all of the chief sensory impulses which 

 have to do with the maintenance of the equilibrium, and is generally 

 included in the nervous apparatus which is supposed to govern this func- 

 tion of our bodies. 



Foville supposed that the cerebellum is the organ of muscular sense, i. e. , the 

 organ by which the mind acquires that knowledge of the actual state and 

 position of the muscles which is essential to the exercise of the will upon them ; 

 and it must be admitted that all the facts just referred to are as well explained 

 on this hypothesis as on that of the cerebellum being the organ for combining 



