In  rare  cases,  considerable  movements  of  the  limbs,  even  of  the  arm,
similar  to  the  associated  movements,  may  be  produced  by  cutaneous  stimu-
lation. The  effect  may  not  be  confined  to  the  paralyzed  side.  Thus,  Nothna-
gel  mentions  a  case  in  which  a  moderate  pinch  of  the  hemiplegic  arm  caused
muscular  contractions  in  the  other  arm  ;  on  a  stronger  pinch  the  contrac-
tions extended  to  the  other  leg,  and,  on  a  still  stronger  pinch,  to  the  leg
also  on  the  same  (hemiplegic)  side,  while  the  arm  that  was  pinched  always

remained  still.*

Muscular  Rigidity. — At  some  period  the  paralyzed  limbs  usually  present
rigidity  of  the  muscles,  which  stiffens  the  limbs  in  a  certain  posture,  and
opposes  passive  movement.  The  attempt  to  overcome  the  rigidity  by  forced
extension  of  the  muscles  causes  pain.  Todd  first  drew  a  distinction  between
two  forms,   "early"  and  "late"  rigidity,  and  to  these  we  must  add  two


*    V.  Ziemssen's  Handbuch,  Bd.  xi,  I,  ii  Auflage,  p.  no.
516


BRAIN.
