﻿1875.] 
  Influence 
  of 
  Electricity 
  on 
  the 
  Hearts 
  of 
  Mollusks. 
  327 
  

  

  and 
  the 
  intervals 
  between 
  the 
  beats 
  generally 
  become 
  increasingly 
  pro- 
  

   longed 
  (see 
  fig. 
  13). 
  

  

  "When 
  the 
  current 
  is 
  maintained 
  for 
  a 
  short 
  time 
  only 
  (10 
  seconds), 
  the 
  

   appearance 
  is 
  produced 
  as 
  if 
  the 
  heart 
  were 
  beating 
  during 
  the 
  whole 
  time 
  

   of 
  the 
  passage 
  of 
  the 
  current 
  (fig. 
  11). 
  

  

  The 
  anodic 
  breaking-beat 
  is, 
  as 
  far 
  as 
  our 
  observations 
  go, 
  always 
  single, 
  

   is 
  never 
  followed 
  by 
  a 
  series 
  of 
  beats 
  (that 
  is, 
  of 
  course, 
  when 
  the 
  

   ventricle 
  is 
  one 
  which 
  is 
  incapable 
  of 
  spontaneous 
  pulsation). 
  

  

  "We 
  conclude 
  that 
  the 
  constant 
  current 
  throws 
  the 
  tissue 
  in 
  the 
  neigh- 
  

   bourhood 
  of 
  the 
  kathode 
  into 
  such 
  a 
  condition 
  as 
  is 
  favourable 
  for 
  the 
  

   development 
  of 
  beats 
  ; 
  that 
  this 
  effect, 
  though 
  taking 
  some 
  time 
  for 
  its 
  

   production, 
  reaches 
  its 
  maximum 
  very 
  soon 
  after 
  the 
  making 
  of 
  the 
  cir- 
  

   cuit, 
  and 
  thenceforward 
  diminishes 
  gradually. 
  

  

  In 
  the 
  neighbourhood 
  of 
  the 
  anode, 
  on 
  the 
  other 
  hand, 
  the 
  tissue 
  is 
  

   thrown 
  into 
  a 
  condition 
  unfavourable 
  for 
  the 
  production 
  of 
  beats, 
  the 
  

   beats 
  which 
  have 
  originated 
  in 
  the 
  kathodic 
  region 
  ceasing 
  as 
  they 
  approach 
  

   the 
  anode. 
  The 
  rebound, 
  however, 
  which 
  follows 
  upon 
  the 
  breaking 
  of 
  

   the 
  circuit 
  develops 
  a 
  beat, 
  with 
  the 
  occurrence 
  of 
  which 
  the 
  tissue 
  

   returns 
  to 
  a 
  normal 
  condition 
  of 
  equilibrium, 
  and 
  no 
  further 
  beats 
  

   occur. 
  

  

  Such 
  are 
  the 
  facts 
  which 
  may 
  be 
  observed 
  when 
  the 
  kathode 
  is 
  placed 
  

   against 
  the 
  auricle, 
  and 
  the 
  anode 
  against 
  the 
  aortic 
  end 
  of 
  the 
  ven- 
  

   tricle. 
  

  

  One 
  would 
  naturally 
  expect 
  that 
  similar 
  results, 
  mutatis 
  mutandis, 
  

   would 
  be 
  obtained 
  when 
  the 
  kathode 
  was 
  placed 
  at 
  the 
  aortic 
  end 
  of 
  the 
  

   ventricle, 
  and 
  the 
  anode 
  at 
  the 
  auricle. 
  Such, 
  however, 
  is 
  not 
  the 
  case. 
  

  

  When 
  the 
  kathode 
  is 
  at 
  the 
  aorta 
  there 
  is 
  only 
  a 
  kathodic 
  making- 
  and 
  

   an 
  anodic 
  breaking-beat. 
  Between 
  the 
  two 
  the 
  ventricle, 
  as 
  a 
  general 
  

   rule, 
  remains 
  perfectly 
  quiet 
  (see 
  figs. 
  12 
  & 
  9). 
  There 
  is 
  therefore 
  a 
  

   functional 
  difference 
  between 
  the 
  auricular 
  and 
  aortic 
  ends 
  of 
  the 
  ven- 
  

   tricle. 
  

  

  Led 
  by 
  the 
  apparent 
  analogy 
  of 
  the 
  vertebrate 
  heart, 
  one 
  might 
  be 
  

   inclined 
  to 
  infer 
  that 
  there 
  was 
  an 
  automatic 
  mechanism 
  present 
  at 
  the 
  

   auricular 
  end 
  of 
  the 
  ventricle, 
  but 
  none 
  at 
  the 
  aortic 
  end. 
  

  

  This 
  view, 
  however, 
  is 
  directly 
  negatived 
  by 
  the 
  following 
  facts 
  : 
  — 
  

   The 
  aortic 
  end 
  will, 
  in 
  active 
  and 
  favourable 
  hearts, 
  continue 
  to 
  beat 
  

   spontaneously 
  for 
  some 
  time 
  after 
  being 
  separated 
  from 
  the 
  rest 
  of 
  the 
  

   ventricle. 
  

  

  WTien, 
  as 
  we 
  shall 
  presently 
  have 
  occasion 
  to 
  mention, 
  a 
  spontaneously 
  

   beating 
  ventricle 
  is 
  submitted 
  to 
  the 
  action 
  of 
  the 
  constant 
  current, 
  the 
  

   beats 
  begin 
  at 
  the 
  aortic 
  end, 
  and 
  are 
  frequently 
  entirely 
  confined 
  to 
  the 
  

   aortic 
  end 
  when 
  that 
  end 
  is 
  made 
  kathodic. 
  This 
  would 
  be 
  impossible 
  

   if 
  the 
  automatic 
  mechanism 
  were 
  confined 
  to 
  the 
  auricular 
  end. 
  We 
  

   have 
  been 
  led 
  to 
  connect 
  the 
  explanation 
  with 
  the 
  shape 
  of 
  the 
  ven- 
  

   tricle 
  

  

  