156 THE SPINAL CORD AND CEREBELLUM 



nerves of chemical action. But the cardinal fact in 

 the whole problem is the sudden, frequent, diverse 

 and great variations in the intensity of this chemical 

 action. This it is which renders a reinforcing organ, 

 such as the cerebellum undoubtedly is, a physiological 

 necessity in the animal economy. If we but look at 

 it in this light we can without any difficulty account 

 for all that is known concerning it — for its co- 

 ordinating and equilibrium controlling functions, for 

 the defective character of these after its removal, for 

 the possibility of the performance of analogous 

 functions in its absence, and for the state of mal- 

 nutrition and death which almost without exception 

 occur. Should not this suffice to convince us that 

 the cerebellum is in reality, as just stated, a reinforcing 

 organ to the rest of the nervous system ? 



We have dealt hitherto with nutrition, and from this 

 part of our subject we now pass to consider briefly 

 the dynamic aspect of reproduction. 



