CORPUS STRIATUM OF MAMMALS 119 



but would leap blindly away — forward if stimulated 

 on the tail, backward if on the nose, and to the oppo- 

 site side if on the side of the head — often continuing 

 until he hit the side of the room. He showed only the 

 most primitive avoiding reactions. There was a strik- 

 ing poverty of movement and the retention of 

 postures which in a normal animal would be corrected. 

 At no time after the operation did the dog show 

 Wilson's disease, paralysis agitans, or muscular 

 rigidity, symptoms usually associated with striatal 

 disease in man. The author concludes that, while a 

 dog lacking the cortex can perform complex move- 

 ments because the striatum apparently replaces in 

 part the cortical functions, if the striatum also is lost 

 there is no longer capacity to combine simple move- 

 ments into more complex patterns. 



These observations seem to show that in mammals 

 the corpus striatum (or at least a part of it) is essen- 

 tial for the performance of all more complex adjust- 

 ments, even those which in still lower animals may 

 be mediated by the thalamus. But they do not make 

 plain just what role it plays. The fact that partial 

 and unsymmetrical injuries to the striatum cause 

 circus movements, motor inco-ordination, tremor, 

 and rigidity suggests that the infkience of the striatum 

 is chiefly (perhaps wholly in higher mammals) dyna- 

 mogenic. 



It is clear that as we pass from lower to higher 

 mammals the relations of the corpus striatum to the 



