﻿Organisms 
  and 
  Nucleic 
  Acid 
  Derivatives 
  on 
  Plant 
  Growth. 
  95 
  

  

  fixing 
  bacteria 
  have 
  the 
  power 
  of 
  elaborating 
  products, 
  which 
  also 
  greatly 
  

   increase 
  the 
  growth 
  of 
  the 
  Lemna 
  plants. 
  

  

  All 
  of 
  these 
  organic 
  materials 
  — 
  the 
  crude 
  nucleic 
  acid 
  derivatives 
  and 
  the 
  

   Azotobacter 
  and 
  Bacillus 
  radicicola 
  growths 
  — 
  give 
  the 
  Folin-Macullum* 
  

   reaction, 
  which 
  is 
  stated 
  to 
  indicate 
  the 
  presence 
  of 
  the 
  growth 
  accessory 
  

   substances 
  — 
  vitamin 
  es 
  — 
  which 
  are 
  so 
  important 
  in 
  animal 
  nutrition. 
  

  

  In 
  connection 
  with 
  the 
  effect 
  of 
  the 
  nucleic 
  acid 
  derivatives 
  it 
  is 
  interesting 
  

   to 
  note 
  that 
  the 
  pure 
  adenine-uracil 
  fraction 
  has 
  not 
  the 
  same 
  effect 
  as 
  the 
  

   crude 
  extract 
  containing 
  all 
  the 
  products 
  of 
  decomposition. 
  This 
  is 
  in 
  

   accordance 
  with 
  the 
  work 
  of 
  Schreiner 
  and 
  Skinner,f 
  who 
  found 
  that 
  pure 
  

   nucleic 
  acid 
  increased 
  the 
  growth 
  of 
  plants 
  in 
  water 
  culture, 
  while 
  some 
  of 
  

   its 
  derivatives, 
  as 
  hypoxanthine 
  and 
  guanine, 
  though 
  still 
  increasing 
  growth, 
  

   were 
  not 
  nearly 
  so 
  effective. 
  

  

  Whatever 
  may 
  be 
  the 
  nature 
  of 
  these 
  growth-promoting 
  substances, 
  it 
  is 
  a 
  

   noteworthy 
  fact 
  that 
  they 
  can 
  be 
  synthesised 
  by 
  the 
  nitrogen-fixing 
  bacteria 
  

   from 
  a 
  carbohydrate 
  and 
  elementary 
  nitrogen. 
  It 
  remains 
  to 
  be 
  seen 
  

   whether 
  the 
  products 
  of 
  other 
  bacteria 
  will 
  bring 
  about 
  the 
  same 
  effect, 
  but 
  

   in 
  working 
  with 
  organisms 
  other 
  than 
  those 
  which 
  fix 
  nitrogen, 
  one 
  great 
  

   drawback 
  is 
  that 
  a 
  start 
  has 
  to 
  be 
  made 
  by 
  supplying 
  a 
  nitrogenous 
  food 
  

   material, 
  so 
  that 
  in 
  the 
  bacterial 
  growth 
  there 
  are 
  present 
  not 
  only 
  nitro- 
  

   genous 
  substances 
  elaborated 
  by 
  the 
  organisms, 
  but 
  also 
  degradation 
  products 
  

   of 
  this 
  food 
  substance. 
  

  

  It 
  may 
  be 
  that 
  among 
  the 
  products 
  of 
  the 
  nitrogen- 
  fixing 
  bacteria 
  are 
  to 
  

   be 
  found 
  substances 
  similar 
  in 
  nature 
  to 
  those 
  contained 
  in 
  the 
  crude 
  nucleic 
  

   acid 
  derivatives 
  from 
  raw 
  peat, 
  and 
  an 
  examination 
  of 
  these 
  products 
  is 
  now 
  

   in 
  progress 
  to 
  determine 
  whether 
  such 
  substances 
  do 
  occur. 
  In 
  any 
  case, 
  the 
  

   experiments 
  recorded 
  throw 
  an 
  additional 
  light 
  on 
  the 
  possible 
  role 
  of 
  the 
  

   nitrogen-fixing 
  bacteria 
  in 
  the 
  soil, 
  especially 
  in 
  view 
  of 
  the 
  generally 
  

   accepted 
  fact 
  that 
  the 
  presence 
  of 
  these 
  organisms 
  is 
  always 
  an 
  indication 
  of 
  

   soil 
  fertility. 
  

  

  The 
  greater 
  part 
  of 
  this 
  work 
  was 
  carried 
  out 
  in 
  1917, 
  but 
  owing 
  to 
  the 
  

   author's 
  illness 
  early 
  in 
  1918 
  he 
  was 
  unable 
  to 
  complete 
  and 
  publish 
  it 
  until 
  

   the 
  present 
  time. 
  He 
  wishes 
  to 
  express 
  his 
  sincere 
  thanks 
  to 
  Miss 
  Mocker- 
  

   idge, 
  D.Sc, 
  for 
  her 
  invaluable 
  assistance 
  in 
  the 
  work. 
  

  

  * 
  Folin 
  and 
  Maculluro, 
  ' 
  Journ. 
  Biol. 
  Cheni.,' 
  vol. 
  11, 
  p. 
  265 
  (1912). 
  

  

  t 
  Schreiner 
  and 
  Skinner, 
  ' 
  U.S. 
  Dept. 
  of 
  Agric, 
  Bureau 
  of 
  Soils,' 
  Bull. 
  No. 
  87. 
  

  

  