226 PHYSIOLOGY OF CENTRAL NERVOUS SYSTEM. 



the general augmenting activity of the cerebellum also a general 

 adaptive or co-ordinating activity. It is precisely this latter feature 

 which stands out in the minds of most physiologists as the 

 characteristic function of the cerebellum, while Luciani considers 

 that it is not demonstrated by clinical or experimental facts, and 

 that even if demonstrated it would have to be considered as a 

 part perhaps a subordinate part of the functional influence of 

 this organ. 



Conclusions as to the General Functions of the Cerebel- 

 lum. It is evident that an authoritative statement of the function 

 or functions of the cerebellum is impossible. It seems quite clear, 

 however, that the organ exerts a regulating influence of some kind 

 upon the neuromuscular apparatus of our so-called voluntary 

 movements. The precise nature of the regulating influence is in 

 dispute, and one who reads the literature finds it difficult at times 

 to separate clearly the different theories proposed, since some 

 authors are content with general statements and others attempt 

 a more specific analysis. On- the whole, it seems desirable at 

 present to hold to the general idea, introduced by Flourens, that 

 the cerebellum is a central organ for co-ordination of voluntary 

 movements, particularly the more complex movements necessary 

 in equilibrium and locomotion. Instead, however, of assuming 

 with Flourens that the cerebellum contains a co-ordinating principle, 

 an expression that means nothing at present, we may assume that 

 it exerts its co-ordinating influence by virtue of the definite nervous 

 mechanisms contained in it that is, by nervous complexes which, 

 on the afferent side, are connected with the peripheral sensory 

 nerves to the vestibule of the ear, the muscles, and the skin, and on 

 the efferent side are in direct or indirect relations with the motor 

 areas of the brain as well as the motor centers in the cord. These 

 mechanisms are inherited structures, but, like other nervous mechan- 

 isms, they are developed by use. The many muscular contractions 

 made in our ordinary movements of equilibrium are learned by ex- 

 perience, and the effects of this training are felt mainly upon these 

 cerebellar paths or mechanisms. We regard the speech center in the 

 cerebrum as a collection of nervous mechanisms in which are stored 

 or preserved the connections necessary to the motor presentation 

 of thoughts, a memory center for the spoken symbols of our con- 

 cepts; it is possible that in the same way we may regard the cere- 

 bellum as a memory center of the muscular movements concerned 

 in equilibrium. The relations of the cerebellum with the motor 

 areas of the cerebrum and the motor centers in the cord are evidently 

 quite complex and far from being fully understood. Moreover, this 

 relationship must vary considerably in different animals. Removal 

 of the cerebrum from a pigeon leaves an animal with almost perfect 



