﻿150 
  

  

  Mr. 
  A. 
  H. 
  Garrod 
  on 
  the 
  

  

  varies 
  very 
  little 
  with 
  different 
  rapidities 
  of 
  pulse, 
  a 
  single 
  example 
  may 
  

   be 
  taken 
  to 
  illustrate 
  the 
  point 
  in 
  question. 
  With 
  the 
  heart 
  beating 
  100 
  

   times 
  in 
  a 
  minute, 
  the 
  time 
  taken 
  by 
  the 
  primary 
  wave 
  in 
  reaching 
  the 
  

   wrist 
  (that 
  is, 
  the 
  length 
  of 
  the 
  first 
  cardio-radial 
  interval 
  with 
  the 
  

   syspasis 
  subtracted) 
  has 
  been 
  shown 
  in 
  a 
  previous 
  Table 
  to 
  be 
  -0021875 
  

   of 
  a 
  minute. 
  Adding 
  to 
  this 
  the 
  interval 
  between 
  the 
  radial 
  and 
  ankle 
  

   primary 
  rise 
  at 
  the 
  same 
  rapidity, 
  which 
  is 
  very 
  nearly 
  '00116 
  of 
  a 
  

   minute, 
  -0033475 
  of 
  a 
  minute 
  is 
  the 
  time 
  taken 
  by 
  the 
  systolic 
  wave 
  in 
  

   travelling 
  from 
  the 
  heart 
  to 
  the 
  ankle. 
  But 
  if 
  this 
  wave 
  went 
  the 
  extra 
  

   distance 
  to 
  the 
  ankle, 
  (52*5—29 
  = 
  ) 
  23-5 
  inches, 
  at 
  the 
  same 
  rate 
  at 
  which 
  

   it 
  reaches 
  the 
  wrist, 
  the 
  length 
  of 
  the 
  first 
  cardio-malleolar 
  interval 
  would 
  

   be 
  -00459375 
  of 
  a 
  minute 
  (29 
  : 
  52-5 
  : 
  : 
  21875 
  : 
  459375) 
  ; 
  but 
  it 
  is 
  only 
  

   •0033475 
  of 
  a 
  minute, 
  which 
  is 
  considerably 
  less; 
  consequently 
  the 
  wave 
  

   augments 
  in 
  rapidity 
  as 
  it 
  gets 
  further 
  from 
  the 
  heart, 
  a 
  phenomenon 
  beyond 
  

   my 
  power 
  to 
  explain. 
  

  

  By 
  superimposing 
  the 
  wrist 
  trace 
  from 
  a 
  simultaneous 
  sphygmogram 
  

   on 
  that 
  from 
  the 
  ankle, 
  it 
  is 
  found 
  that 
  the 
  components 
  of 
  each 
  are 
  of 
  

   exactly 
  similar 
  duration, 
  though 
  the 
  peculiar 
  short 
  interval 
  following 
  the 
  

   dicrotic 
  notch 
  in 
  the 
  latter 
  sometimes 
  complicates 
  the 
  results. 
  This 
  exact 
  

   similarity 
  in 
  length 
  of 
  the 
  different 
  elements 
  of 
  the 
  two 
  pulses 
  is 
  not, 
  as 
  

   will 
  be 
  found 
  by 
  those 
  who 
  attempt 
  to 
  measure 
  them 
  practically, 
  self- 
  

   evident 
  from 
  the 
  tracings 
  themselves 
  ; 
  because 
  the 
  one 
  being 
  slightly 
  later 
  

   than 
  the 
  other, 
  and 
  the 
  watchwork 
  varying 
  in 
  rapidity, 
  gradually 
  increas- 
  

   ing 
  and 
  then 
  declining, 
  the 
  radial, 
  which 
  is 
  the 
  earlier, 
  is 
  slightly 
  the 
  

   shorter 
  in 
  the 
  commencement 
  of 
  the 
  trace 
  and 
  the 
  longer 
  towards 
  its 
  

   end. 
  In 
  the 
  middle 
  of 
  the 
  recording-paper 
  the 
  two 
  coincide. 
  It 
  may 
  

   therefore 
  be 
  said 
  that 
  the 
  compound 
  sphj'gmograph-trace 
  is 
  entirely 
  in 
  

   favour 
  of 
  the 
  correctness 
  of 
  Prop. 
  III. 
  

  

  In 
  conclusion, 
  the 
  following 
  is 
  a 
  summary 
  of 
  the 
  results 
  arrived 
  at 
  in 
  

   this 
  communication 
  : 
  — 
  

  

  I. 
  The 
  lengths 
  of 
  the 
  different 
  elements 
  of 
  the 
  pulse-beat 
  being 
  the 
  

   same 
  in 
  arteries 
  at 
  different 
  distances 
  from 
  the 
  heart, 
  the 
  radial 
  sphyg- 
  

   mograph-trace 
  expresses 
  their 
  duration 
  in 
  the 
  aorta. 
  

  

  II. 
  The 
  cardiosy 
  stole 
  being 
  longer 
  than 
  the 
  sphygmosystole 
  at 
  all 
  

   possible 
  pulse-rates, 
  the 
  excess 
  in 
  the 
  length 
  of 
  the 
  former 
  expresses 
  the 
  

   time 
  required 
  by 
  the 
  heart 
  to 
  reach, 
  from 
  a 
  state 
  of 
  rest, 
  a 
  systolic 
  pressure 
  

   sufficient 
  to 
  open 
  the 
  semilunar 
  valves. 
  This 
  interval, 
  termed 
  the 
  syspasis, 
  

   is 
  constant 
  for 
  any 
  given 
  rapidity 
  of 
  cardiac 
  action, 
  and 
  rapidly 
  decreases 
  

   as 
  the 
  pulse 
  gets 
  quicker, 
  becoming 
  nil 
  at 
  a 
  rate 
  of 
  170 
  a 
  minute. 
  

  

  III. 
  The 
  interval 
  between 
  the 
  commencement 
  of 
  the 
  primary 
  pulse-rise 
  

   in 
  the 
  radial 
  and 
  that 
  in 
  the 
  posterior 
  tibial 
  artery 
  is 
  less 
  than 
  would 
  be 
  

   estimated 
  from 
  the 
  time 
  taken 
  by 
  the 
  same 
  wave 
  in 
  travelling 
  from 
  the 
  

   aortic 
  valve 
  to 
  the 
  radial 
  artery. 
  

  

  The 
  woodcut 
  (p. 
  151) 
  will 
  assist 
  in 
  illustrating 
  the 
  mutual 
  relations 
  of 
  

   the 
  different 
  component 
  parts 
  of 
  the 
  cardiac 
  revolution, 
  as 
  its 
  different 
  

   elements 
  are 
  there 
  shown 
  in 
  their 
  actual 
  relations 
  one 
  to 
  the 
  other. 
  

  

  