The  intermediate  position  of  the  sensory  ganglia,  receiving  as  they  do  the
fibres  from  the  sensory  organs  on  the  one  hand,  and  from  the  cerebron
on  the  other,  points  them  out  to  us  as  the  seat  of  consciousness,  not  <mly
of  what  is  taldng  place  in  the  external  world,  but  also  of  the  operations  if
the  cerebrum  itself-,  and  if  of  consciousness,  then  undoubtedly  of  the  pain
or  pleasure  so  immediately  connected  witli  it.  But  we  have  a  stronger
ground  than  this,  namely,  that  the  very  same  consensual  movements  may  be
excited  by  remembered  or  conceived  sensations  as  by  the  actual  ones;
showing  the  exact  analogy  between  the  downward  action  of  the  cerebrum,
and  the  upward  action  of  the  sensory  nerves,  in  exciting  changes  in  the
sensorium.  We  might  cite  numerous  examples  of  this  kind ;  the  follow-
ing will  suffice.  In  persons  with  irritable  stomachs,  the  act  of  vomiting
may  be  excited  by  an  offensive  smell,  a  nauseous  taste,  or  a  disgustiDg
sight ;  and  the  remembrance  or  conception  of  similar  sensations  will  pro-
duce the  same  effect.  When  the  nervous  system  is  in  the  condition,  that
renders  the  act  of  yawning  easily  excitable^  it  may  be  induced.  Dot  merely


1846.]  Mk.  Noble  on  the  Brain  and  its  Physiology,  513

by  the  sight  or  sound  of  yawning  in  another  person,  but  by  the  mere  idea
of  it,  called  up  by  the  mention  of  the  term.  In  like  manner,  in  hydro-
phobia, the  idea  of  liquids,  called  up  intentionally  or  accidentally,  is  fre-
quently as  efficient  in  exciting  convulsive  paroxysms,  as  the  actual  sight
or  sound  of  them.
