﻿1875.] 
  Influence 
  of 
  Electricity 
  on 
  the 
  Hearts 
  of 
  Mollusks. 
  329 
  

  

  To 
  avoid 
  these 
  difficulties 
  we 
  have 
  generally 
  employed 
  a 
  current 
  so 
  

   weak, 
  that 
  a 
  momentary 
  application 
  of 
  it 
  to 
  the 
  beating 
  heart 
  produced 
  

   no 
  appreciable 
  result. 
  

  

  During 
  the 
  passage, 
  however, 
  of 
  such 
  a 
  weak 
  current 
  very 
  marked 
  

   effects 
  make 
  their 
  appearance. 
  

  

  Whatever 
  the 
  position 
  of 
  the 
  electrodes, 
  whether 
  the 
  current 
  be 
  directed 
  

   longitudinally, 
  with 
  the 
  kathode 
  at 
  the 
  auricular 
  end 
  or 
  at 
  the 
  aortic 
  end, 
  

   or 
  transversely 
  or 
  obliquely, 
  in 
  all 
  cases 
  the 
  normal 
  beat 
  is 
  modified 
  in 
  

   such 
  a 
  way 
  that 
  the 
  contraction 
  begins 
  at 
  the 
  kathode, 
  and 
  is 
  more 
  or 
  

   less 
  limited 
  to 
  the 
  neighbourhood 
  of 
  the 
  kathode. 
  Thus, 
  when 
  the 
  kathode 
  

   is 
  placed 
  at 
  the 
  auricular 
  end 
  of 
  the 
  ventricle, 
  the 
  part 
  immediately 
  round 
  

   the 
  kathode 
  contracts 
  first, 
  and 
  the 
  contraction 
  passes 
  down 
  in 
  a 
  vermi- 
  

   cular 
  manner 
  towards 
  the 
  anode, 
  sometimes 
  a 
  very 
  little 
  way, 
  sometimes 
  a 
  

   considerable 
  distance. 
  When 
  the 
  kathode 
  is 
  placed 
  at 
  the 
  commencement 
  

   of 
  the 
  aorta, 
  the 
  contractions 
  begin 
  at 
  the 
  aorta 
  and 
  pass 
  upwards 
  towards 
  

   the 
  auricular 
  end. 
  

  

  Being 
  thus 
  partial, 
  the 
  beats 
  may 
  be 
  said 
  to 
  be 
  weaker 
  than 
  normal, 
  

   the 
  more 
  so 
  the 
  more 
  they 
  are 
  confined 
  to 
  the 
  kathode. 
  Their 
  feebleness 
  

   seems 
  to 
  be 
  more 
  evident 
  with 
  stronger 
  currents 
  (not 
  so 
  strong, 
  however, 
  

   as 
  to 
  produce 
  an 
  initial 
  contraction) 
  than 
  with 
  weaker 
  ones. 
  

  

  We 
  have 
  not 
  been 
  able 
  to 
  satisfy 
  ourselves 
  as 
  to 
  any 
  marked 
  or 
  constant 
  

   change 
  in 
  the 
  rhythm 
  taking 
  place. 
  

  

  These 
  kathodic 
  beats 
  are 
  succeeded, 
  on 
  breaking 
  the 
  current, 
  by 
  one 
  or 
  

   more 
  markedly 
  strong 
  beats 
  of 
  a 
  reverse 
  direction, 
  beginning 
  at 
  the 
  anode 
  

   and 
  travelling 
  towards 
  the 
  kathode. 
  

  

  In 
  some 
  cases 
  the 
  reversal 
  has 
  been 
  seen 
  to 
  take 
  place 
  during 
  the 
  

   passage 
  of 
  the 
  current, 
  the 
  last 
  few 
  beats 
  beginning 
  at 
  the 
  anode, 
  but 
  not 
  

   then 
  exhibiting 
  the 
  same 
  increase 
  of 
  strength 
  which 
  is 
  seen 
  in 
  the 
  anodic 
  

   beats 
  succeeding 
  the 
  breaking 
  of 
  the 
  current. 
  

  

  This 
  last 
  observation 
  illustrates 
  the 
  fact 
  that 
  the 
  effect 
  of 
  the 
  constant 
  

   current, 
  like 
  that 
  of 
  the 
  tetanizing 
  current, 
  is 
  at 
  its 
  maximum 
  effect 
  near 
  

   the 
  commencement, 
  and 
  thence 
  declines 
  with 
  greater 
  or 
  less 
  rapidity, 
  the 
  

   tissue 
  becoming 
  insensible 
  to 
  the 
  current. 
  In 
  this 
  case 
  insensibility 
  was 
  

   reached 
  after 
  the 
  current 
  had 
  been 
  passing 
  a 
  very 
  short 
  time 
  ; 
  and 
  it 
  is 
  

   interesting 
  to 
  remark 
  that, 
  though 
  the 
  direct 
  effect 
  of 
  the 
  current 
  thus 
  

   became 
  lost, 
  the 
  reaction 
  caused 
  by 
  the 
  action 
  of 
  the 
  current 
  in 
  the 
  first 
  

   part 
  of 
  the 
  period 
  was 
  able 
  to 
  manifest 
  itself 
  by 
  the 
  anodic 
  beats. 
  

  

  Thus, 
  like 
  the 
  initial 
  and 
  final 
  beats 
  observed 
  when 
  the 
  ventricle 
  is 
  at 
  

   rest 
  before 
  the 
  application 
  of 
  the 
  currents, 
  the 
  apparently 
  spontaneous 
  

   beats 
  always 
  originate 
  at 
  the 
  kathode, 
  are 
  more 
  or 
  less 
  confined 
  to 
  the 
  

   kathodic 
  region, 
  and, 
  according 
  to 
  the 
  position 
  of 
  the 
  electrode, 
  may 
  be 
  

   witnessed 
  either 
  at 
  the 
  auricular 
  or 
  at 
  the 
  aortic 
  end. 
  

  

  As 
  with 
  the 
  heart 
  at 
  rest, 
  however, 
  so 
  with 
  the 
  heart 
  in 
  spontaneous 
  

   movement, 
  there 
  is 
  a 
  functional 
  difference 
  between 
  the 
  aortic 
  and 
  the 
  

   auricular 
  ends. 
  

  

  vol. 
  xxtii. 
  2 
  o 
  

  

  