256 ADDENDUM 



of any of the following will abolish decerebrate 

 rigidity : the posterior nerve roots^ antero-lateral 

 region of the cord, superior cerebellar peduncle, or 

 any part of the brain-stem below the red nucleus. 

 Ablation of the cerebellum or of the cerebellar cortex 

 also abolishes tone. Cutting the inferior cerebellar 

 peduncle or the columns of Goll and Burdach do not 

 Influence it. It will be remembered that the ventral 

 cerebellar tract enters by the superior peduncle. 



On the other hand, the inhibitory path cut oft when 

 the mesencephalon is divided is supposed to be the 

 fronto-pontic tract and middle cerebellar peduncle. 

 Stimulation of either of these inhibits any excess of 

 muscular tone. 



The exact location of the tone centre probably has 

 an important bearing upon the pathology of surgical 

 shock. 



