﻿318 
  Dr. 
  M. 
  Foster 
  and 
  Mr. 
  A. 
  G. 
  Dew-Smith 
  on 
  the 
  [Mar. 
  18, 
  

  

  March 
  18, 
  1875. 
  

  

  JOSEPH 
  D 
  ALTON 
  HOOKER, 
  C.B., 
  President, 
  in 
  the 
  Chair. 
  

  

  The 
  Presents 
  received 
  were 
  laid 
  on 
  the 
  table, 
  and 
  thanks 
  ordered 
  for 
  

   them. 
  

  

  The 
  following 
  Papers 
  were 
  read 
  : 
  — 
  

  

  I. 
  "On 
  the 
  Behavionr 
  of 
  the 
  Hearts 
  of 
  Mollusks 
  nnder 
  the 
  

   influence 
  of 
  Electric 
  Currents/' 
  By 
  Dr. 
  M. 
  Foster, 
  F.R.S., 
  

   and 
  A. 
  G. 
  Dew-Smith, 
  B.A., 
  of 
  Trinity 
  College, 
  Cambridge. 
  

   Received 
  February 
  1, 
  1875. 
  

  

  It 
  has 
  already 
  been 
  shown 
  by 
  Dr. 
  Foster 
  (Pfl 
  tiger's 
  'Archiv,' 
  vol. 
  v. 
  p. 
  191) 
  

   that 
  an 
  interrupted 
  current 
  applied 
  directly 
  to 
  the 
  heart 
  of 
  the 
  common 
  

   snail 
  (removed 
  from 
  the 
  body) 
  will 
  cause 
  an 
  arrest 
  of 
  the 
  rhythmic 
  beat, 
  

   the 
  heart 
  remaining 
  in 
  diastole. 
  

  

  The 
  phenomena 
  thus 
  produced 
  are 
  altogether 
  similar 
  to 
  those 
  seen 
  

   when 
  the 
  vertebrate 
  heart 
  is 
  inhibited 
  by 
  stimulation 
  of 
  the 
  pneumo- 
  

   gastric 
  nerve. 
  

  

  This 
  inhibition 
  by 
  direct 
  stimulation 
  requires 
  a 
  current 
  weaker 
  than 
  is 
  

   sufficient 
  to 
  cause 
  tetanus 
  of 
  the 
  heart. 
  It 
  may 
  be 
  witnessed 
  on 
  either 
  

   auricle 
  or 
  ventricle, 
  and 
  is 
  the 
  more 
  easily 
  obtained 
  the 
  more 
  quickly 
  the 
  

   heart 
  is 
  beating. 
  It 
  takes 
  place 
  whatever 
  be 
  the 
  position 
  of 
  the 
  elec- 
  

   trodes 
  ; 
  and 
  we 
  find 
  that 
  it 
  is 
  possible 
  thus 
  to 
  inhibit 
  not 
  only 
  the 
  

   whole 
  ventricle 
  but 
  separate 
  parts 
  of 
  a 
  divided 
  ventricle, 
  provided 
  these 
  

   can 
  be 
  obtained, 
  as 
  they 
  sometimes 
  can, 
  beating 
  with 
  a 
  sufficiently 
  rapid 
  

   rhythm. 
  

  

  "We 
  have 
  found 
  no 
  reason 
  to 
  think 
  that 
  there 
  exists 
  any 
  localized 
  inhi- 
  

   bitory 
  mechanism 
  (corresponding 
  to 
  the 
  sinus 
  venosus 
  ganglia 
  of 
  the 
  

   frog's 
  heart, 
  for 
  instance) 
  any 
  more 
  than 
  a 
  localized 
  automatic 
  me- 
  

   chanism. 
  

  

  This 
  inhibition 
  by 
  direct 
  stimulation 
  is, 
  to 
  say 
  the 
  least, 
  an 
  unusual 
  

   fact 
  ; 
  and 
  the 
  following 
  inquiry 
  was 
  begun 
  in 
  the 
  hope 
  that 
  further 
  study 
  

   of 
  the 
  heart 
  of 
  the 
  same 
  animal, 
  and 
  those 
  of 
  other 
  mollusks, 
  might 
  bring 
  

   to 
  light 
  some 
  explanation 
  of 
  the 
  matter. 
  

  

  We 
  will 
  relate 
  first 
  the 
  results 
  of 
  our 
  experiments 
  with 
  single 
  induc- 
  

   tion-shocks 
  and 
  with 
  the 
  constant 
  current 
  on 
  the 
  snail's 
  heart, 
  and 
  then 
  

   pass 
  on 
  to 
  the 
  facts 
  observed 
  in 
  other 
  mollusks. 
  

  

  "We 
  have 
  in 
  all 
  cases 
  removed 
  the 
  heart 
  from 
  the 
  body, 
  and 
  placed 
  it 
  

   in 
  a 
  watch-glass, 
  in 
  a 
  little 
  snail's 
  blood. 
  It 
  will 
  in 
  this 
  condition 
  con- 
  

   tinue 
  to 
  beat 
  with 
  great 
  regularity 
  for 
  hours. 
  

  

  