﻿1875.] 
  Influence 
  of 
  Electricity 
  on 
  the 
  Hearts 
  of 
  Mollusks. 
  331 
  

  

  end 
  while 
  as 
  yet 
  the 
  current 
  is 
  unable 
  to 
  produce 
  the 
  beats 
  at 
  the 
  aortic 
  

   end, 
  and 
  the 
  result 
  is 
  an 
  apparent 
  general 
  inhibition 
  of 
  the 
  whole 
  

   ventricle. 
  

  

  The 
  inhibition 
  thus 
  produced 
  is, 
  as 
  far 
  as 
  we 
  can 
  see, 
  a 
  distinct 
  inhi- 
  

   bition 
  ; 
  that 
  is, 
  the 
  heart, 
  which 
  previously 
  was 
  beating 
  regularly, 
  stops 
  

   beating 
  when 
  the 
  current 
  is 
  thrown 
  into 
  it, 
  remains 
  in 
  diastole 
  during 
  

   the 
  short 
  time 
  the 
  current 
  continues 
  to 
  pass 
  through 
  it, 
  and 
  resumes 
  its 
  

   beat 
  on 
  the 
  current 
  being 
  removed. 
  

  

  The 
  occurrence 
  of 
  inhibition 
  is, 
  then, 
  here 
  a 
  matter 
  of 
  degree 
  ; 
  it 
  depends 
  

   on 
  the 
  existence 
  of 
  a 
  certain 
  relation 
  between 
  the 
  irritability 
  of 
  the 
  ven- 
  

   tricle' 
  and 
  the 
  strength 
  of 
  the 
  current 
  employed. 
  When 
  a 
  stronger 
  cur- 
  

   rent 
  is 
  employed, 
  the 
  beats, 
  while 
  continuing 
  to 
  be 
  absent 
  at 
  the 
  anode, 
  

   make 
  their 
  appearance 
  at 
  the 
  kathode, 
  and 
  the 
  heart, 
  though 
  beating 
  

   quite 
  differently 
  from 
  the 
  normal, 
  can 
  no 
  longer 
  be 
  said 
  to 
  be 
  inhibited. 
  

   There 
  is 
  no 
  room 
  here 
  for 
  any 
  theory 
  of 
  a 
  special 
  inhibitory 
  mechanism, 
  

   except 
  such 
  a 
  one 
  as 
  would 
  suppose 
  that 
  while 
  the 
  automatic 
  mechanism 
  

   was 
  exalted 
  at 
  the 
  kathode 
  and 
  depressed 
  at 
  the 
  anode, 
  the 
  inhibitory 
  

   mechanism 
  was 
  by 
  weak 
  currents 
  exalted 
  at 
  the 
  anode 
  and 
  depressed 
  at 
  

   the 
  kathode. 
  Such 
  a 
  view 
  would 
  be 
  either 
  simply 
  a 
  clumsy 
  expression 
  

   of 
  facts 
  or, 
  if 
  any 
  thing 
  more, 
  directly 
  opposed 
  to 
  all 
  our 
  experience 
  

   of 
  the 
  behaviour 
  of 
  irritable 
  living 
  matter 
  towards 
  electric 
  currents. 
  

  

  We 
  would 
  now 
  call 
  attention 
  to 
  fig. 
  5. 
  This 
  is 
  the 
  same 
  heart 
  which 
  

   was 
  inhibited 
  by 
  a 
  current 
  passing 
  from 
  the 
  auricle 
  to 
  the 
  aorta, 
  and 
  is 
  

   apparently 
  but 
  little 
  affected 
  by 
  nearly 
  the 
  same 
  strength 
  of 
  current 
  

   passing 
  from 
  the 
  aorta 
  to 
  the 
  auricle. 
  But 
  it 
  will 
  be 
  noticed 
  that, 
  though 
  

   the 
  throwing 
  of 
  the 
  auricular 
  end 
  of 
  the 
  ventricle 
  into 
  a 
  kathodic 
  condi- 
  

   tion 
  does 
  not 
  very 
  much, 
  if 
  at 
  all, 
  increase 
  the 
  beat 
  of 
  the 
  ventricle, 
  the 
  

   withdrawal 
  of 
  the 
  current 
  is 
  followed 
  by 
  a 
  very 
  distinct 
  pause 
  (a) 
  — 
  in 
  fact, 
  

   by 
  an 
  inhibition 
  of 
  short 
  duration. 
  

  

  This 
  pause 
  must 
  be 
  due 
  to 
  a 
  reaction 
  taking 
  place 
  in 
  the 
  kathodic 
  

   region. 
  It 
  can 
  hardly 
  be 
  due 
  to 
  a 
  reaction 
  taking 
  place 
  at 
  the 
  anodic 
  or 
  

   aortic 
  region 
  ; 
  for, 
  as 
  we 
  have 
  already 
  seen, 
  reaction 
  at 
  the 
  anode 
  takes 
  on 
  

   the 
  form 
  of 
  a 
  beat 
  or 
  contraction. 
  We 
  thus 
  get 
  this 
  remarkable 
  result, 
  

   that 
  at 
  the 
  kathode, 
  where 
  the 
  action 
  of 
  the 
  current 
  during 
  its 
  passage 
  is 
  

   favourable 
  to 
  the 
  beat, 
  the 
  after 
  effects, 
  ivhich 
  are 
  in 
  the 
  way 
  of 
  inhibition, 
  

   are 
  more 
  marked 
  than 
  the 
  effects 
  of 
  the 
  current 
  itself, 
  ivhich, 
  as 
  far 
  as 
  they 
  

   go, 
  are 
  in 
  the 
  way 
  of 
  a 
  quickening 
  of 
  the 
  beat. 
  

  

  In 
  other 
  words, 
  at 
  the 
  auricular 
  end 
  of 
  the 
  ventricle, 
  of 
  whose 
  condi- 
  

   tion, 
  by 
  reason- 
  of 
  its 
  greater 
  susceptibility, 
  we 
  are 
  better 
  able 
  to 
  judge 
  

   than 
  of 
  that 
  of 
  the 
  aortic 
  end, 
  we 
  find 
  that, 
  whatever 
  be 
  the 
  direction 
  of 
  

   the 
  current, 
  the 
  total 
  effect 
  of 
  the 
  passage 
  of 
  the 
  current 
  is 
  inhibitory. 
  

   For 
  when 
  the 
  auricular 
  end 
  is 
  anodic, 
  the 
  current 
  produces 
  on 
  that 
  part 
  

   of 
  the 
  ventricle 
  a 
  direct 
  inhibitory 
  effect, 
  which 
  the 
  exalted 
  (kathodic) 
  

   condition 
  of 
  the 
  aortic 
  end 
  is 
  unable 
  to 
  counterbalance 
  ; 
  and 
  when 
  the 
  

   auricular 
  end 
  is 
  kathodic, 
  the 
  depressed 
  (anodic) 
  condition 
  of 
  the 
  aortic 
  

  

  2 
  c 
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