52 KNIGHT DUNLAP 



ties present in many cases, although they are no longer useful, 

 and although they are too slight and fragmentary to serve as 

 actual stimuli for the succeeding transits. Such vestiges are in 

 fact frequently noticed, as in the lip and throat movements which 

 hi many persons accompany silent reading, and have been dem- 

 onstrated by laboratory technique in cases where they were not 

 apparent to casual observation. 



We should expect, if this scheme represents the actual facts, to 

 find that abolition of the cerebellar functions abolishes serial 

 habits which have previously been established: and this is ap- 

 parently what actually happens. We should expect further, to 

 find that after abolition of cerebellar functions, learning is still 

 possible, but that it will never reach a normal level of efficiency: 

 and this also seems to be borne out by observations already made, 

 for action at least. Since all habits follow the same general laws 

 we may confidently expect to find the same results in the case of 

 thought-habits. 



The consideration of the cerebellum as an organ of thought, or 

 rather as an important part of the thought mechanism, is perhaps 

 a startling novelty; but it contradicts none of the known facts of 

 cerebellar function, and necessitates little essential readjustment 

 of present views concerning it. The relatively larger develop- 

 ment of the cerebellum in lower animals as compared with man 

 is a point which, on first consideration, seems to stand in opposi- 

 tion to the hypothesis; but in reality does not. Not only may 

 the cerebellum be supposed to have functions not strictly in- 

 cluded in the associative process such for example, as the regu- 

 lation of muscular tonicity, in conjunction with the semicircular- 

 canal receptors: but also, the proportion of completely habitual 

 (mechanized) activity to variable activity must be assumed to 

 be much larger in the animal than in man. If animals have 

 thought (and there is no reason to suppose they have not), it 

 very probably is more fixed in its sequences than is human 

 thought. 



Whether the cerebellum is the organ responsible for the short- 

 circuiting of serially connected reactions, or whether the mech- 

 anism must be sought elsewhere, it is plain that the reaction-hy- 



