﻿90 
  Dr. 
  W. 
  B. 
  Bottomley. 
  The 
  Effect 
  of 
  Nitrogen-fixing 
  

  

  numbers 
  obtained, 
  resulting 
  in 
  a 
  variable 
  average 
  weight 
  for 
  the 
  series 
  

   concerned. 
  

  

  It 
  should 
  be 
  pointed 
  out 
  here 
  that 
  the 
  increase 
  in 
  number 
  of 
  the 
  plants 
  in 
  

   this 
  experiment 
  does 
  not 
  correspond 
  with 
  the 
  figures 
  given 
  in 
  Table 
  I 
  for 
  a 
  

   similar 
  period. 
  However, 
  all 
  experiments 
  reported 
  were 
  carried 
  out 
  at 
  

   different 
  times, 
  and 
  each 
  one 
  is 
  as 
  complete 
  as 
  possible 
  within 
  itself, 
  for 
  it 
  is 
  

   impossible 
  to 
  make 
  any 
  correct 
  comparisons 
  between 
  trials 
  carried 
  out 
  at 
  

   various 
  periods 
  of 
  the 
  year, 
  owing 
  to 
  the 
  great 
  variation 
  of 
  such 
  factors 
  as 
  

   duration 
  of 
  sunlight, 
  temperature, 
  etc. 
  — 
  factors 
  which 
  have 
  a 
  very 
  great 
  

   influence 
  on 
  the 
  rate 
  of 
  growth 
  and 
  multiplication 
  of 
  the 
  plants. 
  

  

  An 
  examination 
  of 
  the 
  numbers 
  given 
  in 
  Table 
  II 
  shows 
  that 
  both 
  the 
  

   crude 
  nucleic 
  acid 
  derivatives 
  in 
  Series 
  II 
  and 
  the 
  autoclaved 
  Azotobacter 
  in 
  

   Series 
  IV 
  have 
  the 
  effect 
  of 
  markedly 
  increasing 
  the 
  rate 
  of 
  growth 
  and 
  

   multiplication 
  of 
  the 
  Lemna 
  plants 
  ; 
  and 
  the 
  figures 
  in 
  Table 
  III 
  show 
  that 
  

   the 
  average 
  weights 
  of 
  the 
  individual 
  plants 
  in 
  the 
  same 
  series 
  increased 
  

   beyond 
  their 
  original 
  weight, 
  while 
  the 
  weight 
  of 
  the 
  plants 
  in 
  the 
  control 
  

   series 
  steadily 
  decreased. 
  It 
  is 
  evident, 
  therefore, 
  that 
  both 
  the 
  crude 
  nucleic 
  

   acid 
  derivatives 
  and 
  the 
  Azotobacter 
  have 
  a 
  growth-promoting 
  effect 
  ; 
  but 
  

   when 
  the 
  two 
  are 
  added 
  together 
  to 
  the 
  Detmer's 
  solution, 
  as 
  in 
  Series 
  V, 
  

   their 
  combined 
  effect 
  is 
  far 
  greater 
  than 
  the 
  sum 
  of 
  their 
  effects 
  when 
  added 
  

   separately, 
  as 
  in 
  Series 
  II 
  and 
  IV, 
  and 
  is 
  approximately 
  equal 
  to 
  that 
  of 
  the 
  

   water 
  extract 
  of 
  bacterised 
  peat 
  in 
  Series 
  VI. 
  It 
  would 
  therefore 
  appear 
  that 
  

   the 
  growth-promoting 
  substances 
  in 
  these 
  two 
  liquids 
  are 
  dissimilar 
  in 
  their 
  

   action 
  upon 
  the 
  plant, 
  and 
  that 
  they 
  are 
  in 
  some 
  manner 
  complementary 
  to 
  

   one 
  another 
  ; 
  for 
  were 
  they 
  similar 
  in 
  their 
  role 
  in 
  the 
  plant 
  metabolism, 
  it 
  

   would 
  be 
  expected 
  that 
  the 
  effect 
  of 
  the 
  two 
  when 
  supplied 
  together 
  would 
  

   be 
  approximately 
  equal 
  to 
  the 
  sum 
  of 
  their 
  separate 
  effects. 
  

  

  The 
  remarkable 
  similarity 
  between 
  the 
  results 
  produced 
  by 
  the 
  extract 
  

   from 
  1 
  grm. 
  of 
  bacterised 
  peat, 
  on 
  the 
  one 
  hand, 
  and 
  the 
  crude 
  nucleic 
  

   derivatives 
  from 
  1 
  grm. 
  of 
  raw 
  peat, 
  together 
  with 
  the 
  Azotobacter 
  growth, 
  

   on 
  the 
  other, 
  is 
  readily 
  explained. 
  It 
  may 
  reasonably 
  be 
  supposed 
  that 
  

   the 
  water 
  extract 
  from 
  1 
  grm. 
  of 
  bacterised 
  peat 
  contains 
  a 
  quantity 
  of 
  the 
  

   nucleic 
  acid 
  derivatives 
  approximately 
  equal 
  to 
  that 
  in 
  1 
  grm. 
  of 
  raw 
  peat, 
  

   these 
  substances 
  having 
  been 
  rendered 
  water-soluble 
  during 
  the 
  process 
  of 
  

   " 
  bacterisation 
  " 
  ; 
  while, 
  since 
  Azotobacter 
  chroococcum 
  is 
  very 
  largely 
  used 
  

   during 
  this 
  process, 
  and 
  multiplies 
  rapidly 
  in 
  the 
  peat 
  basis, 
  it 
  is 
  probable 
  

   that 
  the 
  water 
  extract 
  of 
  the 
  material 
  contains 
  a 
  quantity 
  of 
  the 
  products 
  of 
  

   this 
  organism 
  comparable 
  to 
  the 
  proportions 
  used 
  in 
  the 
  above 
  experiment, 
  

   since 
  this 
  proportion 
  would 
  amount 
  to 
  only 
  1*68 
  per 
  cent, 
  of 
  the 
  weight 
  of 
  

   the 
  peat. 
  

  

  