﻿120 
  

  

  Mr. 
  W. 
  J. 
  Young 
  and 
  others. 
  Effect 
  of 
  

  

  (1913) 
  to 
  the 
  washing 
  out 
  of 
  carbon 
  dioxide 
  from 
  the 
  lungs 
  by 
  the 
  vigorous 
  

   ventilation. 
  

  

  In 
  the 
  hot 
  room 
  experiments 
  the 
  percentage 
  of 
  carbon 
  dioxide 
  did 
  not 
  

   show 
  any 
  constant 
  variation, 
  whereas 
  Hill 
  and 
  Flack 
  (1909) 
  in 
  their 
  hot- 
  

   bath 
  experiment, 
  observed 
  a 
  marked 
  decrease 
  in 
  the 
  carbon 
  dioxide 
  tension, 
  

   owing 
  to 
  the 
  increased 
  rate 
  of 
  respiration 
  due 
  to 
  the 
  heat. 
  

  

  Loss 
  in 
  body 
  loeight. 
  — 
  The 
  temporary 
  loss 
  in 
  body 
  weight 
  brought 
  about 
  

   by 
  exercise, 
  and 
  which 
  is 
  mainly 
  due 
  to 
  loss 
  of 
  water, 
  is 
  naturally 
  con- 
  

   siderable 
  in 
  the 
  tropics, 
  on 
  account 
  of 
  the 
  increased 
  perspiration. 
  As 
  shown 
  

   in 
  Table 
  VII 
  the 
  loss 
  bears 
  relationship 
  to 
  the 
  effort, 
  time, 
  and 
  external 
  

   heat. 
  It 
  was 
  quite 
  a 
  common 
  occurrence 
  to 
  lose 
  as 
  much 
  as 
  1 
  kgrm. 
  in 
  

   weight 
  during 
  a 
  walk 
  of 
  one 
  hour 
  at 
  a 
  moderate 
  pace, 
  and 
  in 
  one 
  instance 
  

   as 
  much 
  as 
  3200 
  grm. 
  (Experiment 
  No. 
  IV 
  in 
  Table) 
  was 
  lost 
  during 
  a 
  two 
  

   hours' 
  walk. 
  The 
  loss 
  of 
  weight 
  in 
  the 
  hot 
  room 
  amounted 
  to 
  between 
  

   500 
  and 
  1200 
  grm. 
  in 
  one 
  hour. 
  In 
  several 
  exercise 
  experiments 
  quoted 
  in 
  

   the 
  Table, 
  the 
  subjects 
  were 
  weighed 
  in 
  their 
  clothing 
  so 
  that 
  the 
  loss 
  

   represents 
  only 
  the 
  water 
  evaporated 
  and 
  not 
  the 
  total 
  water 
  lost 
  from 
  

   the 
  body. 
  

  

  The 
  loss 
  of 
  weight 
  represents 
  in 
  the 
  main 
  loss 
  of 
  water 
  secreted 
  as 
  per- 
  

   spiration 
  ; 
  a 
  certain 
  amount 
  of 
  water 
  is 
  lost 
  in 
  the 
  expired 
  air, 
  but 
  as 
  the 
  

   air 
  inspired 
  is 
  not 
  far 
  from 
  the 
  saturation 
  point 
  this 
  amount 
  is 
  small. 
  The 
  

   loss 
  in 
  weight 
  due 
  to 
  respiratory 
  exchange 
  may 
  be 
  neglected.* 
  In 
  the 
  hot 
  

   room, 
  where 
  the 
  humidity 
  was 
  very 
  high, 
  practically 
  the 
  total 
  loss 
  in 
  weight 
  

   is 
  due 
  to 
  perspiration. 
  

  

  The 
  question 
  as 
  to 
  the 
  source 
  from 
  which 
  the 
  perspiration 
  is 
  derived 
  has 
  

   been 
  discussed 
  by 
  Hunt 
  (1912), 
  who 
  estimated 
  the 
  percentage 
  of 
  haemoglobin 
  

   in 
  the 
  blood 
  before 
  and 
  after 
  prolonged 
  sweating 
  in 
  a 
  hot 
  room. 
  He 
  found 
  

   that 
  the 
  haemoglobin 
  figures 
  remained 
  constant, 
  and 
  concluded 
  from 
  this 
  that 
  

   no 
  concentration 
  of 
  the 
  blood 
  had 
  taken 
  place 
  and 
  that 
  therefore 
  the 
  water 
  

   excreted 
  in 
  the 
  sweat 
  was 
  derived 
  from 
  the 
  tissues 
  and 
  not 
  from 
  the 
  blood 
  

   serum. 
  A 
  similar 
  experiment 
  was 
  carried 
  out 
  by 
  Haldane 
  and 
  Priestley 
  (1916) 
  

  

  * 
  In 
  the 
  course 
  of 
  another 
  investigation 
  by 
  one 
  of 
  us 
  (W. 
  J. 
  Y.) 
  the 
  respiratory 
  

   exchange 
  of 
  two 
  of 
  the 
  subjects 
  was 
  determined 
  by 
  means 
  of 
  a 
  Zuntz 
  portable 
  meter, 
  

   during 
  a 
  walk 
  of 
  15 
  minutes 
  at 
  a 
  rate 
  of 
  3 
  miles 
  per 
  hour, 
  and 
  the 
  figures 
  obtained 
  may 
  

   be 
  quoted 
  here 
  to 
  show 
  that 
  only 
  an 
  insignificant 
  portion 
  of 
  the 
  weight 
  lost 
  is 
  accounted 
  

   for 
  in 
  this 
  way. 
  

  

  In 
  this 
  experiment 
  carbon 
  dioxide 
  was 
  evolved 
  at 
  the 
  rate 
  of 
  107 
  and 
  119 
  grm. 
  per 
  hour 
  

   by 
  the 
  two 
  subjects 
  respectively, 
  and 
  oxygen 
  absorbed 
  at 
  the 
  rate 
  of 
  96 
  and 
  108 
  grm. 
  

   per 
  hour. 
  The 
  loss 
  in 
  weight 
  due 
  to 
  respiratory 
  exchange 
  was 
  therefore 
  only 
  11 
  grm. 
  

   per 
  hour 
  in 
  each 
  case. 
  

  

  In 
  another 
  experiment, 
  one 
  subject 
  during 
  an 
  hour 
  in 
  the 
  hot 
  chamber 
  lost 
  about 
  

   7 
  grm. 
  in 
  weight 
  due 
  to 
  the 
  respiratory 
  exchange. 
  

  

  