50 KNIGHT DUNLAP 



for the mechanism which is capable of providing the short 

 circuits. 



At the present time, the cerebellum is the organ to which the 

 supplementation of the muscular system may most plausibly be 

 attributed, and its known connection with the muscular activi- 

 ties and with learning render it advisable to consider the probable 

 cerebellar functions before seeking elsewhere for a short circuiting 

 mechanism. The accumulated knowledge concerning the cere- 

 bellum is too voluminous, and too full of difficulties to be dis- 

 cussed here in any detail, and I shall attempt only the sketching 

 of the scheme which at present seems most significant. 12 



Whatever the principal functions of the cerebellum in the 

 lower animals, it may be assumed in man to have acquired the 

 possibility of receiving efferent current from the cerebrum, and of 

 redirecting current back to the cerebrum, just as the striped 

 muscles are known to do. Assuming further the development 

 of a " point to point" correspondence between the cerebellum and 

 the striated muscular system, 13 we would have the possibility of 

 a split in the efferent leg of the primary reacti6n-arc, so that cur- 

 rent might be sent both to the muscle or group of muscles and to 

 the corresponding cerebellar cells. Afferent current (to the cere- 

 brum) from these cerebellar cells would tend to be drained into 

 the channels of the succeeding reaction transits in accordance 

 with the fundamental principles of integration. A series of neu- 

 ral transits would therefore be established paralleling the series 

 of complete reactions represented in figure 1 ; a series of transits 

 between the cerebellum and the cerebrum : and the establishment 

 of that system would have very important consequences. 



11 For summaries of observations and theories, Luciani, Physiology, vol. Ill, 

 chap. VIII, and Andr6-Thomas, Cerebellar Functions translated by W. Conyers 

 Herring, (Nervous and Mental Disease Monograph No. 12), should be consulted. 



18 This ' 'point to point" correspondence is not necessarily anatomical. It may 

 be a correspondence between certain cerebellar cell-groups and certain definite 

 muscular functions: or it may be entirely functional. The relations between 

 cerebellar cells and other portions of the body is known to be of a sort which is 

 easily modified, one part of the cerebellum being capable of assuming functions 

 previously exercised by another. 



