﻿Vegetable 
  Assimilation 
  and 
  Respiration. 
  

  

  251 
  

  

  too 
  strong 
  or 
  too 
  weak 
  an 
  illumination. 
  The 
  leaves, 
  when 
  sufficiently 
  

   greened, 
  were 
  transferred 
  to 
  the 
  apparatus, 
  and 
  their 
  photosynthetic 
  activity 
  

   measured 
  by 
  their 
  output 
  of 
  oxygen. 
  Except 
  where 
  otherwise 
  stated, 
  they 
  

   were 
  transferred 
  to 
  the 
  apparatus 
  immediately 
  after 
  exposure 
  to 
  light. 
  

   Between 
  the 
  periods 
  during 
  which 
  the 
  assimilation 
  was 
  measured, 
  the 
  

   chamber 
  was 
  disconnected 
  from 
  the 
  apparatus, 
  the 
  hydrogen 
  replaced 
  by 
  air, 
  

   and 
  the 
  chamber, 
  with 
  the 
  leaves 
  still 
  in 
  it, 
  placed 
  in 
  the 
  dark. 
  In 
  this 
  way 
  

   the 
  leaf 
  was 
  kept 
  at 
  one 
  tone 
  of 
  greenness 
  for 
  many 
  days. 
  

  

  At 
  the 
  completion 
  of 
  the 
  experiment 
  each 
  set 
  of 
  leaves 
  was 
  dried 
  at 
  

   100° 
  C. 
  until 
  no 
  further 
  loss 
  of 
  weight 
  was 
  observed. 
  

  

  Results. 
  — 
  The 
  details 
  of 
  the 
  experiments 
  on 
  Pkaseolus 
  set 
  out 
  in 
  the 
  

   Appendix 
  are 
  summarised 
  in 
  Table 
  A 
  below. 
  

  

  The 
  assimilatory 
  power 
  is 
  expressed 
  as 
  the 
  output 
  of 
  oxygen 
  in 
  cubic 
  

   centimetres 
  per 
  gramme 
  dry- 
  weight 
  of 
  leaf 
  per 
  hour. 
  The 
  volume 
  is 
  reduced 
  

   to 
  0° 
  C. 
  and 
  760 
  mm. 
  of 
  mercury. 
  It 
  is 
  realised 
  that 
  this 
  is 
  a 
  measure 
  of 
  

   " 
  apparent 
  " 
  and 
  not 
  of 
  " 
  real 
  " 
  assimilation, 
  since 
  oxygen 
  consumption, 
  due 
  

   to 
  respiration, 
  is 
  neglected, 
  and 
  consequently, 
  when 
  the 
  assimilatory 
  power 
  is 
  

   given 
  as 
  x 
  c.cs., 
  a 
  value 
  of 
  about 
  1*3 
  c.cs., 
  as 
  shown 
  by 
  the 
  respiration 
  

   experiments, 
  should 
  be 
  added. 
  The 
  " 
  apparent 
  " 
  assimilation, 
  however, 
  is 
  

   suitable 
  for 
  the 
  comparative 
  purposes 
  of 
  these 
  experiments, 
  and 
  to 
  sub- 
  

   stantiate 
  the 
  conclusions 
  drawn. 
  

  

  Table 
  A. 
  — 
  Phaseolus 
  vulgaris. 
  Assimilatory 
  Power 
  of 
  Young 
  Seedling 
  Leaves 
  

   of 
  different 
  Ages 
  and 
  Degrees 
  of 
  Greenness 
  as 
  Measured 
  by 
  Oxygen 
  

   Production. 
  

  

  Day 
  from 
  

   sowing. 
  

  

  Assimilatory 
  power. 
  

  

  Expt. 
  I. 
  

  

  Expt. 
  Ia. 
  

  

  Expt. 
  II. 
  

  

  Expt. 
  m. 
  

  

  Expt. 
  VI. 
  

  

  0-7th 
  

   8th 
  

   9th 
  

   10th 
  

   11th 
  

   12th 
  

   13th 
  

   14th 
  

   15th 
  

   16th 
  

   17th 
  

  

  Grown 
  

   Greened 
  by 
  li 
  

  

  1- 
  3 
  

  

  2- 
  5 
  

   In 
  dark 
  

  

  7-0 
  

   7-0 
  

  

  in 
  dark, 
  

   ghting 
  in 
  air. 
  

   In 
  dark. 
  

  

  4- 
  1 
  

  

  5- 
  5 
  

  

  6- 
  7 
  

  

  Greened 
  by 
  li 
  

   7-8 
  

   9-5 
  

   10 
  -o 
  

  

  ghting 
  in 
  air. 
  

   In 
  dark 
  

  

  l6'-5 
  

  

  Greened 
  by 
  lighting 
  in 
  air. 
  

  

  3) 
  J) 
  

  

  12 
  -0 
  

  

  