﻿Dr. 
  D. 
  Ferrier 
  on 
  the 
  Brain 
  of 
  Monkeys. 
  423 
  

  

  XIII. 
  Strong 
  contraction 
  of 
  the 
  platysma, 
  and 
  retraction 
  of 
  the 
  left 
  

   angle 
  of 
  the 
  month. 
  

  

  The 
  results 
  of 
  stimulation 
  of 
  this 
  centre 
  agree 
  with 
  each 
  other, 
  and 
  

   indicate 
  a 
  centre 
  for 
  the 
  platysma. 
  The 
  frequent 
  retraction 
  of 
  the 
  angle 
  

   of 
  the 
  mouth 
  observed 
  on 
  causing 
  clenching 
  of 
  the 
  fist 
  is 
  explained 
  by 
  the 
  

   proximity 
  of 
  the 
  two 
  centres 
  to 
  each 
  other. 
  

  

  Island 
  of 
  Eeil 
  (central 
  lobe), 
  within 
  fissure 
  of 
  Sylvius 
  : 
  — 
  

  

  Owing 
  to 
  the 
  central 
  lobe 
  in 
  the 
  monkey 
  being 
  completely 
  concealed 
  

   within 
  the 
  lips 
  of 
  the 
  fissure 
  of 
  Sylvius, 
  mechanical 
  injury 
  and 
  consider- 
  

   able 
  haemorrhage 
  is 
  necessarily 
  caused 
  in 
  the 
  attempt 
  to 
  expose 
  it 
  clearly. 
  

   This 
  is 
  mentioned 
  as 
  a 
  possible 
  explanation 
  of 
  the 
  negative 
  results, 
  but 
  

   it 
  is 
  not 
  sufficient 
  to 
  account 
  for 
  the 
  apparent 
  non-excitability 
  of 
  this 
  

   region. 
  

  

  The 
  island 
  was 
  exposed 
  and 
  experimented 
  on 
  in 
  monkeys 
  IX. 
  and 
  

   XIII. 
  

  

  IX. 
  Electrization 
  of 
  the 
  island 
  of 
  Eeil 
  gave 
  no 
  results. 
  

  

  Some 
  movements 
  of 
  the 
  mouth 
  were 
  caused 
  during 
  the 
  intro- 
  

   duction 
  of 
  the 
  electrodes 
  within 
  the 
  fissure, 
  but 
  were 
  referred 
  to 
  

   stimulation 
  of 
  the 
  mouth-centres 
  in 
  close 
  proximity. 
  

  

  XIII. 
  The 
  result 
  in 
  this 
  case 
  was 
  also 
  negative. 
  

  

  To 
  test 
  this 
  matter 
  more 
  fully, 
  another 
  monkey, 
  not 
  among 
  those 
  

   already 
  numbered, 
  was 
  experimented 
  on 
  on 
  December 
  10. 
  

  

  The 
  lips 
  of 
  the 
  fissure 
  of 
  Sylvius 
  were 
  carefully 
  separated, 
  without 
  

   causing 
  much 
  injury 
  or 
  haemorrhage. 
  After 
  the 
  ha)morrhage 
  had 
  entirely 
  

   ceased, 
  the 
  electrodes 
  were 
  applied 
  directly 
  to 
  the 
  surface 
  of 
  the 
  central 
  

   lobe. 
  

  

  No 
  effect 
  was 
  observed. 
  

  

  After 
  the 
  animal 
  had 
  been 
  allowed 
  to 
  rest 
  for 
  some 
  time, 
  it 
  was 
  then 
  

   tested 
  as 
  to 
  the 
  excitability 
  of 
  the 
  other 
  centres. 
  The 
  hand, 
  leg, 
  and 
  

   mouth 
  could 
  as 
  usual 
  be 
  acted 
  on 
  by 
  stimulation 
  of 
  their 
  respective 
  

   centres. 
  

  

  The 
  electrodes, 
  insulated 
  up 
  to 
  the 
  point, 
  were 
  again 
  applied 
  to 
  the 
  

   island 
  of 
  Eeil. 
  

  

  No 
  result 
  was 
  observed. 
  

  

  Stronger 
  and 
  continuous 
  stimulation 
  gave 
  rise 
  to 
  choreic 
  spasms 
  of 
  the 
  

   angle 
  of 
  the 
  mouth. 
  This 
  was 
  attributed 
  to 
  diffusion 
  of 
  the 
  current, 
  

   owing 
  to 
  its 
  being 
  strengthened, 
  and 
  irritation 
  of 
  the 
  proximate 
  centres 
  

   for 
  the 
  angle 
  of 
  the 
  mouth. 
  

  

  Another 
  application 
  of 
  the 
  electrodes 
  within 
  the 
  lower 
  end 
  of 
  the 
  

   fissure 
  caused 
  movements 
  of 
  the 
  mouth 
  and 
  tongue. 
  These 
  also 
  may 
  

   have 
  been 
  due 
  to 
  conduction 
  to 
  the 
  mouth-centres 
  already 
  described. 
  

  

  Beyond 
  these, 
  stimulation 
  of 
  the 
  island 
  of 
  Eeil 
  yields 
  negative 
  results. 
  

  

  