﻿332 
  Dr. 
  M. 
  Foster 
  and 
  Mr. 
  A. 
  Gr. 
  Dew- 
  Smith 
  on 
  the 
  [Mar. 
  18, 
  

  

  end 
  hinders 
  any 
  great 
  increase 
  in 
  the 
  total 
  force 
  of 
  the 
  beats 
  — 
  so 
  that 
  the 
  

   direct 
  effect 
  of 
  the 
  current 
  is 
  manifested 
  only, 
  if 
  at 
  all, 
  in 
  a 
  quickening 
  

   of 
  the 
  beat, 
  while 
  the 
  after 
  effect 
  is 
  distinctly 
  inhibitory, 
  to 
  such 
  an 
  extent 
  

   as 
  not 
  to 
  be 
  obscured 
  by 
  the 
  reaction, 
  in 
  the 
  way 
  of 
  exaltation, 
  which 
  

   takes 
  place 
  at 
  the 
  (anodic) 
  aortic 
  end. 
  In 
  other 
  words, 
  whichever 
  its 
  

   direction, 
  in 
  the 
  one 
  case 
  by 
  action, 
  in 
  the 
  other 
  by 
  reaction, 
  a 
  sufficiently 
  

   weak 
  current 
  leaves 
  a 
  balance 
  in 
  favour 
  of 
  inhibition. 
  

  

  Though, 
  by 
  reason 
  of 
  the 
  less 
  susceptibility 
  of 
  the 
  aortic 
  end 
  and 
  the 
  

   consequently 
  slighter 
  development 
  in 
  that 
  region 
  of 
  a 
  rhythmic 
  beat, 
  

   we 
  are 
  less 
  able 
  to 
  judge 
  of 
  what 
  is 
  going 
  on 
  in 
  that 
  region 
  during 
  the 
  

   passage 
  of 
  the 
  current, 
  we 
  may, 
  we 
  venture 
  to 
  think, 
  assume 
  that 
  the 
  

   changes 
  there 
  are 
  of 
  fundamentally 
  the 
  same 
  kind 
  as 
  at 
  the 
  auricular 
  end 
  — 
  

   that 
  is 
  to 
  say, 
  that 
  the 
  total 
  effect 
  of 
  the 
  passage 
  of 
  the 
  current 
  would 
  

   at 
  this 
  end 
  too 
  be 
  greater 
  in 
  the 
  direction 
  of 
  inhibition 
  than 
  of 
  exaltation. 
  

   A 
  sufficiently 
  weak 
  current, 
  then, 
  passed 
  lengthwise 
  through 
  the 
  ventricle 
  

   in 
  either 
  direction, 
  whether 
  from 
  aorta 
  to 
  auricle 
  or 
  from 
  auricle 
  to 
  aorta, 
  

   has 
  an 
  inhibitory 
  effect 
  (when 
  the 
  period 
  of 
  reaction 
  is 
  included) 
  greater 
  

   than 
  its 
  exalting 
  effect. 
  

  

  If 
  we 
  suppose 
  such 
  a 
  current 
  to 
  be 
  momentarily 
  passed 
  through 
  the 
  

   ventricle 
  between 
  any 
  two 
  beats, 
  its 
  effect 
  therefore, 
  as 
  far 
  as 
  it 
  went, 
  

   would 
  be 
  to 
  prolong 
  the 
  diastole. 
  The 
  effect 
  might 
  not 
  be 
  very 
  obvious 
  ; 
  

   it 
  might 
  be 
  so 
  small 
  as 
  to 
  escape 
  detection 
  by 
  itself, 
  but 
  it 
  might 
  be 
  made 
  

   manifest 
  in 
  the 
  following 
  way 
  : 
  — 
  The 
  effect 
  of 
  the 
  current, 
  as 
  we 
  have 
  

   in 
  all 
  cases 
  seen, 
  whether 
  exalting 
  or 
  inhibitory, 
  takes 
  some 
  time 
  to 
  esta- 
  

   blish, 
  and 
  lasts 
  longer 
  than 
  the 
  actual 
  passage 
  of 
  the 
  current. 
  Hence, 
  if 
  

   a 
  momentary 
  current 
  like 
  the 
  above 
  be 
  succeeded 
  before 
  the 
  next 
  beat 
  by 
  

   a 
  second 
  similar 
  one, 
  the 
  effect 
  of 
  the 
  second 
  would 
  be 
  added 
  to 
  the 
  first, 
  

   and 
  the 
  diastole 
  still 
  further 
  prolonged. 
  By 
  means 
  of 
  momentary 
  cur- 
  

   rents, 
  repeated 
  so 
  rapidly 
  that 
  the 
  effect 
  of 
  one 
  had 
  not 
  passed 
  off 
  before 
  

   the 
  next 
  began 
  to 
  tell, 
  the 
  diastole 
  would 
  be 
  so 
  prolonged 
  that 
  the 
  inhibi- 
  

   tory 
  effect 
  of 
  the 
  current 
  would 
  be 
  undeniable. 
  

  

  Moreover, 
  though 
  we 
  have 
  used 
  the 
  longitudinal 
  application 
  of 
  the 
  

   current 
  as 
  a 
  means 
  of 
  analyzing 
  its 
  effects, 
  there 
  is 
  nothing 
  to 
  prevent 
  a 
  

   similar 
  explanation 
  being 
  given 
  of 
  the 
  inhibitory 
  effects 
  of 
  a 
  weak 
  momen- 
  

   tary 
  current 
  passed 
  transversely, 
  or 
  in 
  any 
  direction, 
  through 
  the 
  ventricle 
  

   or 
  through 
  the 
  auricle. 
  The 
  inhibitory 
  effect 
  of 
  the 
  longitudinal 
  current 
  

   depends 
  essentially 
  on 
  the 
  fact 
  that 
  the 
  total 
  effect 
  of 
  the 
  current, 
  when 
  

   the 
  after 
  effects 
  are 
  included, 
  is 
  one 
  of 
  depression, 
  though 
  it 
  has 
  partial 
  

   elements 
  of 
  exaltation 
  ; 
  and 
  this 
  will 
  hold 
  good 
  whatever 
  be 
  the 
  position 
  

   of 
  the 
  electrodes, 
  provided 
  that 
  the 
  current 
  be 
  of 
  a 
  certain 
  intensity 
  in 
  

   relation 
  to 
  the 
  irritability 
  of 
  the 
  tissue. 
  

  

  "We 
  conclude, 
  then, 
  that 
  the 
  clear 
  and 
  obvious 
  inhibition 
  brought 
  about 
  

   by 
  sufficiently 
  rapid 
  repetitions 
  of 
  momentary 
  currents 
  (such 
  as 
  single 
  

   induction-shocks) 
  of 
  a 
  certain 
  feebleness 
  is 
  due 
  to 
  the 
  summation 
  of 
  a 
  

   number 
  of 
  slight 
  inhibitions, 
  the 
  occurrence 
  of 
  each 
  single 
  inhibition 
  

  

  