﻿252 
  Mr. 
  G. 
  E. 
  Briggs. 
  Experimental 
  Researches 
  on 
  

  

  Table 
  A 
  — 
  continued. 
  

  

  Day 
  from 
  

   sowing. 
  

  

  Expt. 
  IIIa. 
  

  

  Expt. 
  IV 
  j 
  Expt. 
  IVa. 
  

  

  Expt. 
  III. 
  

  

  Expt. 
  V. 
  

  

  0-7th 
  

   8th 
  

   9th 
  

   10th 
  

   11th 
  

   12th 
  

   13th 
  

   14th 
  

   15th 
  

   16th 
  

   17th 
  

   18th 
  

   19th 
  

   20th 
  

  

  Grown 
  in 
  dark. 
  

   Greened 
  by 
  li 
  ghting 
  in 
  air. 
  

  

  Grown 
  

  

  in 
  dark. 
  

  

  In 
  dark. 
  

  

  5 
  -0 
  

  

  10 
  -4 
  „ 
  

  

  9'-2 
  

  

  Greened 
  by 
  li 
  

  

  ghting 
  in 
  air. 
  

   In 
  dark. 
  

  

  6 
  6 
  

   7-8 
  

   9 
  1 
  

  

  7 
  3 
  

   7 
  

  

  Greened 
  on 
  plant. 
  

  

  12-0 
  

  

  Note. 
  — 
  In 
  Expts. 
  I, 
  Ia, 
  II, 
  IIa, 
  IV, 
  and 
  IVa, 
  the 
  period 
  of 
  greening 
  was 
  approximately 
  the 
  

   same, 
  and 
  likewise 
  the 
  tone 
  of 
  greenness 
  (" 
  green-yellow 
  ") 
  developed. 
  

  

  The 
  leaves 
  of 
  Expts. 
  Ill 
  and 
  IIIa 
  were 
  greened 
  for 
  a 
  longer 
  period, 
  and 
  the 
  tone 
  of 
  green 
  

   obtained 
  was 
  deeper 
  (" 
  yellow-green"). 
  In 
  Expts. 
  V 
  and 
  VI 
  the 
  leaves 
  were 
  full 
  normal 
  green 
  

   and 
  are 
  included 
  for 
  comparative 
  purposes. 
  

  

  The 
  conditions 
  during 
  illumination 
  were 
  the 
  same 
  in 
  all 
  experiments. 
  Temperature 
  11°-16° 
  C. 
  

  

  The 
  value 
  given 
  for 
  the 
  assimilatory 
  power 
  is 
  the 
  average 
  for 
  the 
  period 
  during 
  which 
  the 
  

   leaves 
  were 
  illuminated 
  in 
  the 
  apparatus 
  — 
  a 
  preliminary 
  of 
  about 
  one 
  hour 
  being 
  allowed 
  in 
  each 
  

   ■case. 
  For 
  details 
  see 
  Appendix. 
  

  

  The 
  first 
  noticeable 
  feature 
  of 
  the 
  results 
  recorded 
  is 
  that 
  the 
  assimilatory 
  

   power 
  of 
  leaves, 
  which 
  have 
  developed 
  a 
  very 
  small 
  portion 
  of 
  their 
  normal 
  

   •content 
  of 
  green 
  pigment, 
  is 
  a 
  quantity 
  which 
  depends 
  more 
  upon 
  the 
  age 
  of 
  

   the 
  leaf 
  than 
  upon 
  its 
  colour. 
  The 
  leaves 
  of 
  Expts. 
  I 
  and 
  II 
  are 
  comparable 
  in 
  

   that 
  they 
  are 
  from 
  plants 
  which 
  were 
  sown 
  together. 
  The 
  main 
  difference 
  is 
  

   that 
  the 
  leaves 
  of 
  Expt. 
  I 
  were 
  exposed 
  to 
  light 
  on 
  the 
  eighth 
  day 
  from 
  

   sowing, 
  whilst 
  those 
  of 
  Expt. 
  II 
  were 
  five 
  days 
  older 
  when 
  exposed. 
  The 
  

   assimilation 
  of 
  the 
  former 
  on 
  the 
  first 
  day 
  after 
  greening 
  was 
  only 
  1*3 
  units, 
  

   whilst 
  that 
  of 
  the 
  older 
  leaves 
  was 
  7'8. 
  Still 
  more 
  striking 
  is 
  a 
  comparison 
  

   of 
  Expts. 
  Ill 
  and 
  IV. 
  The 
  younger 
  leaves 
  of 
  Expt. 
  Ill 
  produced 
  no 
  surplus 
  

   oxygen 
  during 
  the 
  seven 
  hours 
  they 
  were 
  in 
  the 
  apparatus. 
  These 
  leaves 
  

   had 
  been 
  exposed 
  to 
  light 
  for 
  25 
  hours, 
  and 
  during 
  that 
  time 
  had 
  developed 
  a 
  

   yellow-green 
  colour. 
  On 
  the 
  other 
  hand, 
  those 
  of 
  Expt. 
  IV, 
  which 
  were 
  four 
  

   days 
  older, 
  showed 
  an 
  output 
  of 
  6 
  - 
  6 
  units 
  of 
  oxygen, 
  although 
  they 
  had 
  been 
  

   exposed 
  to 
  light 
  only 
  13 
  hours, 
  during 
  wbich 
  time 
  they 
  had 
  become 
  only 
  

   green-yellow. 
  

  

  The 
  second 
  feature 
  of 
  note 
  is 
  that, 
  whatever 
  the 
  amount 
  of 
  the 
  oxygen 
  

   output 
  on 
  the 
  first 
  day 
  after 
  greening, 
  it 
  increased 
  during 
  the 
  following 
  days 
  

  

  