ANATOMY, PHYSIOLOGY, OF NERVOUS SYSTEM. 457 



act to his sensations without the direct intervention of his 

 brain. 



SPECIAL PHYSIOLOGY OF THE MEDULLA. 



In the medulla, too, we find reflex centers, but the reflex 

 centers are here of a higher kind. They are still involuntary 

 and largely outside of the control of the will, but are not the 

 simple muscular reflexes of the cord. They are the higher 

 reflexes governing complicated systems in the body. In 

 fact, it may be proper to speak of the reflexes here as the 

 systemic reflexes. Instances of the reflex centers of breath- 

 ing, circulation and temperature have already been noted. 

 In addition to these we find in the medulla some of the 

 simpler reflexes, the sensation occasioning which are derived 

 from the special senses. 



THE PHYSIOLOGY OF THE CEREBELLUM. 



It is exceedingly difficult to determine definitely the func- 

 tions of such complicated structures as the cerebrum and 

 the cerebellum. The structures are so delicate and the 

 methods of operation upon them to determine their func- 

 tions so coarse that it is frequently difficult to argue from 

 cause to effect. One can easily imagine how much progress 

 would be made by an individual trying to understand the 

 workings of a watch by standing off at a distance and firing 

 pistol shots at it and then noting the result ; firing first at the 

 hand, then the face of the watch, then spring or case. One 

 can easily see the almost utter hopelessness of ever getting 

 at a complete knowledge of a watch by such rude means, 

 and yet incisions or stimulations, in fact all of the experi- 

 ments made on the brains of animals have been relatively 

 as rough and inexact as the firing of a pistol into the deli- 

 cate watch. A few general points are, however, available. 



It seems probable that the function of the cerebellum is 

 that of a large motor center to whose jurisdiction are con- 

 signed the ordinary habitual motions of the body ; walking, 

 running, in case of animals, flying or swimming. These 

 motor habits are doubtless acquired painfully and slowly 



