﻿336 
  Dr. 
  M. 
  Foster 
  and 
  Mr. 
  A. 
  G. 
  Dew-Smith 
  on 
  the 
  [Mar. 
  18, 
  

  

  Out 
  into 
  two, 
  so 
  as 
  to 
  divide 
  one 
  aorta 
  and 
  the 
  branchial 
  sinus 
  of 
  one 
  

   side 
  from 
  the 
  other 
  aorta 
  and 
  the 
  branchial 
  sinus 
  of 
  the 
  other 
  side, 
  each 
  

   half 
  of 
  the 
  Sepias 
  heart 
  continued 
  to 
  beat 
  rhythmically. 
  

  

  Hence 
  there 
  cannot 
  be 
  a 
  single 
  automatic 
  nervous 
  centre 
  for 
  the 
  ven- 
  

   tricle 
  of 
  the 
  Sepia's 
  heart. 
  

  

  No 
  nerve 
  could 
  be 
  discovered, 
  the 
  stimulation 
  of 
  which 
  would 
  produce 
  

   inhibition 
  of 
  the 
  heart 
  after 
  the 
  fashion 
  of 
  the 
  vertebrate 
  pnemnogastric. 
  

  

  The 
  interrupted 
  current 
  applied 
  directly 
  to 
  the 
  ventricle 
  did, 
  under 
  

   favourable 
  circumstances, 
  produce 
  a 
  stoppage 
  of 
  the 
  rhythm, 
  the 
  heart 
  

   remaining 
  in 
  diastole 
  and 
  resuming 
  its 
  beat 
  on 
  the 
  removal 
  of 
  the 
  

   current. 
  

  

  Single 
  induction-shocks 
  and 
  the 
  make 
  and 
  break 
  of 
  a 
  constant 
  current 
  

   appeared 
  to 
  produce 
  the 
  same 
  effects 
  in 
  Sepia 
  as 
  in 
  the 
  snail, 
  sometimes 
  

   causing 
  a 
  contraction 
  and 
  sometimes 
  having 
  as 
  a 
  result 
  a 
  more 
  or 
  less 
  

   distinct 
  inhibition. 
  

  

  During 
  the 
  passage 
  of 
  a 
  constant 
  current 
  exactly 
  the 
  same 
  phenomena 
  

   were 
  apparent 
  as 
  in 
  the 
  case 
  of 
  the 
  snail, 
  the 
  beats 
  always 
  starting 
  from 
  

   the 
  kathode 
  and 
  travelling 
  towards 
  the 
  anode. 
  This 
  effect 
  could, 
  in 
  fact, 
  

   be 
  seen 
  even 
  more 
  distinctly 
  in 
  the 
  case 
  of 
  Sepia 
  than 
  of 
  the 
  snail. 
  By 
  

   placing 
  the 
  electrodes 
  in 
  a 
  proper 
  position 
  the 
  course 
  of 
  the 
  pulsation 
  

   along 
  the 
  ventricle 
  might 
  be 
  at 
  pleasure 
  reversed. 
  

  

  In 
  general 
  we 
  may, 
  we 
  believe, 
  safely 
  conclude 
  that 
  what 
  we 
  have 
  

   found 
  to 
  be 
  the 
  case 
  with 
  the 
  snail's 
  heart, 
  holds 
  good 
  also, 
  in 
  funda- 
  

   mental 
  points, 
  for 
  the 
  heart 
  of 
  Sepia. 
  

  

  It 
  was 
  hoped 
  that 
  the 
  large 
  specimens 
  of 
  Aplysia 
  which 
  were 
  at 
  hand 
  

   at 
  the 
  Station 
  would 
  prove 
  of 
  valuable 
  assistance. 
  The 
  difficulty 
  of 
  

   working 
  with 
  them, 
  owing 
  to 
  the 
  contractions 
  of 
  the 
  body 
  and 
  the 
  un- 
  

   willingness 
  of 
  the 
  heart 
  to 
  beat 
  out 
  of 
  the 
  body, 
  prevented, 
  however, 
  

   any 
  satisfactory 
  observations 
  being 
  made 
  with 
  them. 
  

  

  As 
  in 
  Sepia, 
  so 
  in 
  Aplysia, 
  no 
  nerve 
  could 
  be 
  found, 
  stimulation 
  of 
  

   which 
  would 
  cause 
  direct 
  inhibition 
  of 
  the 
  heart. 
  

  

  Three 
  specimens 
  of 
  Salpa 
  came 
  into 
  Mr. 
  Dew-Smith's 
  hands. 
  

  

  In 
  these 
  two 
  platinum 
  electrodes 
  were 
  thrust 
  through 
  the 
  body, 
  so 
  

   that 
  their 
  points 
  came 
  to 
  the 
  neighbourhood 
  of 
  the 
  heart, 
  the 
  pulsations 
  

   of 
  which 
  could 
  be 
  readily 
  observed 
  with 
  the 
  naked 
  eye 
  and 
  counted. 
  The 
  

   position 
  of 
  the 
  electrodes 
  was 
  such 
  that 
  a 
  current 
  sent 
  through 
  them 
  

   would 
  pass 
  in 
  large 
  measure 
  lengthwise 
  through 
  the 
  heart. 
  

  

  The 
  effect 
  of 
  the 
  interrupted 
  current 
  was 
  very 
  remarkable. 
  During 
  its 
  

   passage 
  the 
  heart, 
  which, 
  according 
  to 
  wont, 
  had 
  previously 
  been 
  alter- 
  

   nating 
  in 
  direction 
  after 
  every 
  6 
  to 
  15 
  beats, 
  continued 
  to 
  beat 
  for 
  two 
  

   minutes 
  entirely 
  in 
  one 
  direction 
  at 
  a 
  quickened 
  rate. 
  No 
  inhibition 
  could 
  

   be 
  produced, 
  even 
  with 
  strong 
  currents. 
  

  

  We 
  quote 
  this 
  single 
  observation 
  because 
  it 
  was 
  the 
  only 
  one 
  that 
  

   could 
  be 
  made. 
  Bad 
  weather 
  setting 
  in 
  prevented 
  any 
  more 
  Salpce 
  being 
  

   obtained 
  before 
  Mr. 
  Dew-Smith 
  left 
  for 
  England 
  ; 
  otherwise 
  it 
  would 
  

  

  