﻿338 
  Dr. 
  M. 
  Foster 
  and 
  Mr. 
  A. 
  G. 
  Dew-Smith 
  on 
  the 
  [Mar. 
  18, 
  

  

  carry 
  it 
  on. 
  Otherwise 
  there 
  would 
  be 
  not 
  a 
  regular 
  beat, 
  but 
  an 
  irre- 
  

   gular 
  skirmish 
  of 
  contractions. 
  

  

  We 
  are 
  driven, 
  therefore, 
  to 
  conclude 
  that 
  in 
  the 
  normal 
  condition, 
  

   where 
  the 
  tissue 
  is 
  physiologically 
  continuous, 
  there 
  are 
  means 
  of 
  com- 
  

   munication 
  between 
  all 
  parts 
  ; 
  so 
  that 
  the 
  auricular 
  half, 
  for 
  instance, 
  on 
  

   the 
  one 
  hand, 
  feels, 
  if 
  we 
  may 
  use 
  the 
  phrase, 
  what 
  is 
  going 
  on 
  in 
  the 
  

   aortic 
  half, 
  and, 
  on 
  the 
  other, 
  exerts 
  an 
  influence 
  on 
  those 
  changes 
  in 
  

   order 
  to 
  accommodate 
  them 
  to 
  the 
  changes 
  taking 
  place 
  in 
  itself, 
  and 
  

   vice 
  versa. 
  

  

  "We 
  believe 
  that 
  all 
  our 
  knowledge 
  of 
  protoplasm 
  (and 
  we 
  might 
  point 
  

   especially 
  to 
  the 
  harmonious 
  working 
  of 
  groups 
  of 
  cilia 
  and 
  ciliated 
  cells) 
  

   favours 
  the 
  idea 
  of 
  the 
  existence 
  of 
  such 
  a 
  consensus 
  among 
  the 
  several 
  

   parts 
  of 
  any 
  mass 
  of 
  protoplasm 
  which 
  acts 
  together 
  as 
  a 
  whole. 
  JNor 
  

   ought 
  there 
  really 
  to 
  be 
  any 
  difficulty 
  in 
  supposing 
  such 
  communications 
  

   to 
  be 
  effected 
  by 
  molecular 
  movements 
  in 
  the 
  undifferentiated 
  protoplasm; 
  

   for 
  there 
  must 
  be 
  in 
  protoplasm 
  many 
  kinds 
  of 
  currents 
  and 
  internal 
  

   motions 
  for 
  which 
  we 
  have 
  at 
  present 
  no 
  names. 
  We 
  might 
  further 
  

   urge 
  that 
  there 
  must 
  be 
  in 
  undifferentiated 
  protoplasm 
  the 
  rudiments 
  of 
  

   all 
  the 
  fundamental 
  functions 
  present 
  in 
  the 
  differentiated 
  structures 
  of 
  

   higher 
  animals. 
  Thus 
  the 
  process 
  by 
  which 
  the 
  condition 
  of 
  the 
  aortic 
  

   region 
  of 
  the 
  snail's 
  ventricle 
  is 
  communicated 
  to 
  the 
  auricular 
  region 
  

   seems 
  to 
  be 
  the 
  rudiment 
  of 
  the 
  muscular 
  sense. 
  

  

  Adopting 
  some 
  such 
  view 
  as 
  this, 
  we 
  are 
  naturally 
  led 
  to 
  what 
  we 
  

   venture 
  to 
  think 
  is 
  a 
  more 
  satisfactory 
  interpretation 
  of 
  the 
  part 
  played 
  

   by 
  ganglia 
  in 
  rhythmic 
  and 
  automatic 
  movements 
  than 
  the 
  one 
  com- 
  

   monly 
  adopted. 
  

  

  The 
  prevalent 
  conception, 
  based 
  on 
  the 
  view 
  put 
  forward 
  by 
  Sir 
  James 
  

   Paget 
  in 
  his 
  well-known 
  Croonian 
  lecture, 
  if 
  we 
  understand 
  it 
  aright, 
  is 
  

   somewhat 
  as 
  follows 
  : 
  — 
  Taking, 
  for 
  instance, 
  the 
  automatic 
  ganglia 
  of 
  the 
  

   heart, 
  motor 
  impulses 
  are 
  rhythmically 
  generated 
  in 
  the 
  ganglionic 
  nerve- 
  

   cells, 
  as 
  the 
  result 
  of 
  the 
  nutrition 
  of 
  these 
  nerve-cells 
  themselves, 
  in- 
  

   fluenced, 
  according 
  to 
  circumstances, 
  by 
  afferent 
  impulses 
  starting 
  from 
  

   sentient 
  surfaces 
  internal 
  or 
  external 
  of 
  the 
  heart 
  itself, 
  or 
  brought 
  from 
  

   afar 
  by 
  the 
  pneumogastric 
  or 
  other 
  nerves. 
  

  

  These 
  motor 
  impulses 
  reaching 
  the 
  muscular 
  fibres 
  call 
  forth 
  a 
  beat, 
  

   the 
  contractile 
  elements 
  being, 
  so 
  to 
  speak, 
  mere 
  passive 
  instruments 
  of 
  

   the 
  nerve-cells, 
  their 
  condition 
  affecting 
  the 
  beat 
  only 
  so 
  far 
  as 
  its 
  force 
  

   is 
  concerned, 
  inasmuch 
  as, 
  with 
  the 
  same 
  stimulus, 
  the 
  contraction 
  will 
  

   be 
  greater 
  in 
  a 
  more 
  irritable, 
  and 
  smaller 
  in 
  a 
  less 
  irritable 
  fibre. 
  

  

  Now 
  every 
  one 
  must 
  have 
  felt 
  a 
  difficulty 
  in 
  supposing 
  that 
  the 
  nutri- 
  

   tion 
  of 
  a 
  few 
  minute 
  nerve-cells 
  should 
  be 
  all 
  in 
  all, 
  while 
  that 
  of 
  the 
  

   large 
  mass 
  of 
  the 
  continually 
  and 
  rapidly 
  changing 
  muscular 
  tissue 
  should 
  

   go 
  for 
  nothing 
  in 
  determining 
  what 
  is 
  at 
  least 
  quite 
  as 
  important 
  as 
  the 
  

   force 
  of 
  each 
  contraction, 
  viz. 
  the 
  rate 
  of 
  rhythm. 
  Moreover 
  such 
  a 
  view 
  

   puts, 
  to 
  a 
  certain 
  extent, 
  asunder 
  what 
  nature 
  has 
  evidently, 
  by 
  intricate 
  

  

  