458 



STUDIES IN ADVANCED PHYSIOLOGY. 



by the cerebrum, as for instance, in the case of an infant 

 learning to walk or crawl. As they are repeated over and 

 over again they become more and more habitual. They 

 seem to be delegated more and more by the conscious cere- 

 brum to the lower cerebel- 

 lum, and in this way the 

 activity of the cerebrum 

 left to higher functions in- 

 stead of continually wast- 

 ing its strength in looking 

 after the contraction of 

 the muscles in moving the 

 body. 



If, for instance, the cere- 

 bellum be removed from 

 the brain of a pigeon the 

 animal sits quietly, seems 

 to be conscious of dan- 

 ger; seems, in short, to 

 retain most of its psychic 

 functions, but is awkward 

 in its walk, stumbles and 

 falls easily, and flies with 

 the greatest difficulty. It 

 has lost control, apparent- 

 ly, of the motions which 

 originally it performed 

 with rapidity and precis- 

 ion. Removals of the cere- 

 bellum from other animals 

 have in a general way 

 shown similar results. 



Without going into fur- 

 ther detail the whole point 

 may be summed up in the statement that it is the governing 

 center for the general habitual motions of the body. The 

 physiological value of this is at once clear when we remem- 



Fig. 146. SECTION OF THE CORTEX OF CERE- 

 BELLUM. (After Sankey.) 

 a, pia-mater with contained blood-vessels; 

 &, external layer of gray matter; c, layer of cor- 

 puscles (nerve cells) of Purkinje; d, inner gran- 

 ule layer; e, medulla. 



