﻿144 
  

  

  Mr. 
  A. 
  H. 
  Garrod 
  on 
  the 
  

  

  The 
  corollary 
  to 
  Proposition 
  III. 
  leads 
  to 
  theoretical 
  results 
  of 
  con- 
  

   siderable 
  importance 
  ; 
  for 
  as 
  the 
  duration 
  of 
  the 
  different 
  elements 
  of 
  

   each 
  beat 
  in 
  the 
  radial 
  artery 
  is 
  the 
  same 
  as 
  that 
  in 
  the 
  commencing 
  

   aorta, 
  by 
  superposing 
  the 
  sphygmograph-trace 
  upon 
  the 
  cardiograph-trace 
  

   at 
  any 
  given 
  pulse-rate, 
  a 
  comparison 
  can 
  be 
  made 
  between 
  the 
  duration 
  

   of 
  the 
  different 
  physiological 
  changes 
  going 
  on 
  in 
  the 
  heart 
  and 
  those 
  

   going 
  on 
  in 
  the 
  commencing 
  aorta 
  ; 
  in 
  other 
  words, 
  the 
  time 
  during 
  

   which 
  the 
  ventricular 
  and 
  arterial 
  systoles 
  are 
  continuous 
  can 
  be 
  ascer- 
  

   tained 
  with 
  precision 
  by 
  an 
  indirect 
  method, 
  which 
  alone 
  is 
  possible 
  in 
  

   the 
  human 
  subject- 
  

   Taking 
  the 
  equations 
  given 
  in 
  Prop. 
  I. 
  and 
  Prop. 
  II., 
  the 
  length 
  of 
  the 
  

   systolic 
  portion 
  of 
  each 
  beat 
  in 
  the 
  cardiograph- 
  and 
  sphygmograph- 
  

   traces 
  may 
  be 
  calculated 
  with 
  facility 
  for 
  any 
  value 
  of 
  a\ 
  From 
  the 
  

   equations 
  above 
  given, 
  namely, 
  scy=20 
  and 
  #?/=47^/#, 
  it 
  is 
  found 
  

   that 
  the 
  length 
  of 
  the 
  arterial 
  systole 
  is 
  shorter 
  than 
  the 
  cardiac, 
  as 
  

   would 
  be 
  expected, 
  because 
  the 
  cardiograph-trace 
  is 
  an 
  indication 
  of 
  the 
  

   movements 
  in 
  the 
  muscular 
  walls 
  of 
  the 
  heart, 
  and 
  not 
  of 
  the 
  contained 
  

   blood, 
  and 
  because 
  a 
  certain 
  tension 
  must 
  be 
  reached 
  by 
  the 
  intraven- 
  

   tricular 
  blood 
  at 
  the 
  commencement 
  of 
  the 
  systole 
  before 
  it 
  can 
  push 
  

   open 
  the 
  aortic 
  valves. 
  

  

  The 
  sphygmosystole 
  being 
  therefore 
  shorter 
  than 
  the 
  cardiac 
  systole, 
  it 
  

   becomes 
  a 
  question, 
  when 
  an 
  attempt 
  is 
  made 
  to 
  superpose 
  them 
  exactly, 
  

   as 
  to 
  whether 
  they 
  correspond 
  at 
  the 
  commencement 
  or 
  the 
  end 
  of 
  the 
  

   cardiosystole. 
  This 
  is 
  easily 
  answered 
  ; 
  for 
  independent 
  observations 
  

   show 
  the 
  points 
  in 
  both 
  at 
  which 
  the 
  semilunar 
  valves 
  of 
  the 
  aorta 
  close. 
  

   These 
  points 
  in 
  the 
  traces 
  must 
  evidently 
  be 
  simultaneous, 
  which 
  is 
  

   therefore 
  the 
  same 
  thing 
  as 
  saving 
  that 
  the 
  interval 
  between 
  the 
  greater 
  

   cardiosystole 
  and 
  the 
  shorter 
  sphygmosystole 
  is 
  at 
  the 
  commencement 
  of 
  

   the 
  cardiosystole. 
  This 
  interval, 
  the 
  existence 
  of 
  which 
  is 
  well 
  indicated 
  

   in 
  Marey's 
  cardio-aortic 
  tracings 
  from 
  the 
  horse, 
  may 
  be 
  termed 
  the 
  

   sijsjpasis 
  (the 
  time 
  during 
  which 
  the 
  ventricles 
  are 
  raising 
  the 
  pressure 
  of 
  

   their 
  contained 
  blood) 
  ; 
  and 
  the 
  following 
  Table, 
  obtained 
  from 
  the 
  two 
  

   equations 
  just 
  mentioned, 
  gives 
  its 
  length 
  at 
  different 
  pulse-rates 
  : 
  — 
  

  

  •0018753' 
  at 
  cc= 
  36 
  approximately. 
  

   •00132986' 
  „ 
  a? 
  = 
  49 
  

   •000931' 
  „ 
  a? 
  = 
  64 
  

   •00004199' 
  „ 
  a7=81 
  

   •0003766' 
  „ 
  a? 
  =100 
  

   •00024645' 
  „ 
  a?=121 
  

   •000118' 
  „ 
  a?=144 
  

   •000000' 
  „ 
  a?=l70 
  

  

  Prom 
  this 
  Table 
  it 
  is 
  evident 
  that 
  the 
  syspasis 
  varies 
  considerably 
  

   with 
  different 
  rapidities 
  of 
  pulse, 
  decreasing 
  rapidly 
  with 
  increase 
  in 
  the 
  

  

  