﻿Organisms 
  and 
  Nucleic 
  Acid 
  Derivatives 
  on 
  Plant 
  Growth. 
  85 
  

  

  counting, 
  and 
  this 
  was 
  repeated 
  each 
  week 
  until 
  the 
  end 
  of 
  the 
  experiment. 
  

   When 
  necessary 
  the 
  sets 
  were 
  even 
  quartered, 
  three-fourths 
  of 
  each 
  dish 
  

   being 
  discarded. 
  The 
  figures 
  obtained 
  are 
  shown 
  in 
  the 
  Table 
  below, 
  the 
  

   numbers 
  given 
  being 
  the 
  total 
  numbers 
  from 
  the 
  original 
  ten 
  plants 
  in 
  each 
  

   dish, 
  and 
  not 
  the 
  fractions 
  retained 
  at 
  the 
  weekly 
  countings. 
  

  

  Table 
  I. 
  

  

  Series. 
  

  

  No. 
  

  

  1st 
  

   week. 
  

  

  2nd 
  

   week. 
  

  

  3rd 
  

   week. 
  

  

  4th 
  

   week. 
  

  

  5th 
  

   week. 
  

  

  6th 
  

   week. 
  

  

  I. 
  

  

  r 
  

  

  '% 
  v 
  

  

  22 
  

  

  80 
  

  

  212 
  

  

  576 
  

  

  1,248 
  

  

  1,984 
  

  

  

  2 
  

  

  31 
  

  

  79 
  

  

  174 
  

  

  416 
  

  

  1,056 
  

  

  1,568 
  

  

  Detmer's 
  Solution 
  .. 
  

  

  ■ 
  H 
  

  

  . 
  3 
  

  

  30 
  

  

  82 
  

  

  166 
  

  

  464 
  

  

  1,024 
  

  

  1,696 
  

  

  

  4 
  

  

  32 
  

  

  82 
  

  

  194 
  

  

  432 
  

  

  1,088 
  

  

  1,524 
  

  

  

  

  5 
  

  

  35 
  

  

  86 
  

  

  210 
  

  

  512 
  

  

  1,248 
  

  

  1,824 
  

  

  

  

  

  32 
  -0 
  

  

  81 
  -8 
  

  

  191 
  -2 
  

  

  480 
  

  

  1,132 
  "8 
  

  

  1,779-2 
  

  

  II. 
  

  

  

  

  

  

  

  

  

  

  

  f 
  

  

  6 
  

  

  40 
  

  

  135 
  

  

  532 
  

  

  2,624 
  

  

  10,240 
  

  

  25,120 
  

  

  Detmer's 
  Solution 
  

  

  7 
  

  

  42 
  

  

  142 
  

  

  502 
  

  

  2,656 
  

  

  12,224 
  

  

  27,776 
  

  

  + 
  

  

  

  8 
  

  

  37 
  

  

  130 
  

  

  564 
  

  

  2,720 
  

  

  10,656 
  

  

  27,872 
  

  

  Azotobaeter 
  

  

  

  9 
  

  

  36 
  

  

  127 
  

  

  478 
  

  

  2,512 
  

  

  11,808 
  

  

  24,064 
  

  

  

  L 
  

  

  10 
  

  

  43 
  

  

  159 
  

  

  600 
  

  

  2,848 
  

  

  11,040 
  

  

  28,832 
  

  

  Mean 
  

  

  

  

  39 
  -6 
  

  

  138 
  -6 
  

  

  535 
  -2 
  

  

  2,672 
  

  

  11,193 
  -6 
  

  

  26,732 
  -8 
  

  

  At 
  the 
  end 
  of 
  the 
  experiment 
  the 
  plants 
  from 
  three 
  dishes 
  in 
  each 
  set 
  

   were 
  used 
  for 
  a 
  determination 
  of 
  the 
  dry 
  weight, 
  and 
  from 
  the 
  figures 
  so 
  

   obtained 
  the 
  dry 
  weight 
  of 
  100 
  plants 
  was 
  calculated. 
  The 
  results 
  are 
  shown 
  

   below 
  : 
  — 
  

  

  Mgrm. 
  

  

  Dry 
  weight 
  of 
  100 
  plants 
  at 
  beginning 
  of 
  experiment 
  14 
  - 
  8 
  

  

  „ 
  „ 
  from 
  Series 
  I 
  at 
  end 
  of 
  experiment 
  ... 
  10-0 
  

  

  „ 
  „ 
  from 
  Series 
  II 
  „ 
  „ 
  ... 
  18 
  - 
  2 
  

  

  It 
  is 
  evident 
  from 
  these 
  figures 
  that 
  the 
  addition 
  of 
  the 
  sterilised 
  

   Azotobaeter 
  chroococcum 
  to 
  the 
  culture 
  solution 
  not 
  only 
  resulted 
  in 
  an 
  

   increased 
  rate 
  of 
  multiplication 
  of 
  the 
  Lemna 
  plants, 
  but 
  also 
  enabled 
  them 
  

   to 
  increase 
  their 
  original 
  size, 
  while 
  the 
  weight 
  of 
  the 
  control 
  plants 
  showed 
  a 
  

   corresponding 
  decrease. 
  It 
  therefore 
  appears 
  that 
  part, 
  at 
  least, 
  of 
  the 
  

   beneficial 
  effect 
  of 
  the 
  water 
  extract 
  of 
  bacterised 
  peat 
  is 
  due 
  to 
  the 
  products 
  

   of 
  the 
  nitrogen-fixing 
  bacteria 
  which 
  it 
  contains 
  ; 
  and 
  if 
  such 
  an 
  effect 
  as 
  that 
  

   recorded 
  above 
  be 
  produced 
  by 
  a 
  definite 
  addition 
  of 
  bacterial 
  substance, 
  it 
  is 
  

  

  G 
  2 
  

  

  