﻿204 
  

  

  Prof. 
  B. 
  Moore 
  and 
  Mr. 
  T. 
  A. 
  Webster. 
  

  

  nitrogenous 
  compounds 
  in 
  the 
  form 
  of 
  proteins; 
  it 
  is 
  probable 
  that 
  the 
  

   ultra-microscopic 
  particles, 
  called 
  filter-passers, 
  which 
  can 
  pass 
  through 
  a 
  

   Chamberland 
  filter 
  and 
  yet 
  can 
  reproduce 
  themselves 
  in 
  organic 
  media, 
  and 
  

   transmit 
  diseases, 
  also 
  contain 
  organic 
  nitrogenous 
  substances. 
  Their 
  very 
  

   specific 
  reactions 
  show 
  these 
  ultra-microscopic 
  germs 
  to 
  be 
  highly 
  organised 
  

   systems, 
  on 
  the 
  path 
  from 
  the 
  inorganic 
  to 
  the 
  organic. 
  It 
  is 
  hence 
  futile 
  to 
  

   seek 
  at 
  the 
  level 
  of 
  bacteria 
  for 
  the 
  origin 
  of 
  the 
  organic 
  ; 
  the 
  first 
  stage 
  must 
  

   have 
  been 
  an 
  inorganic 
  colloidal 
  solution-aggregate, 
  capable 
  of 
  utilising 
  

   sunlight 
  and 
  of 
  building 
  up 
  on 
  its 
  surface 
  or 
  in 
  its 
  meshes 
  organic 
  substances 
  

   as 
  a 
  forerunner 
  for 
  the 
  still 
  ultra-microscopic 
  living 
  cell. 
  The 
  powers 
  of 
  

   such 
  a 
  synthesising 
  colloid 
  in 
  evolving 
  more 
  complex 
  forms 
  of 
  matter 
  would 
  

   soon 
  have 
  been 
  exhausted 
  had 
  it 
  not 
  been 
  able 
  to 
  fix 
  nitrogen 
  as 
  well 
  as 
  

   carbon 
  from 
  its 
  environment. 
  This 
  power 
  of 
  nitrogen 
  fixation, 
  as 
  evolution 
  

   proceeded, 
  must 
  necessarily 
  have 
  been 
  passed 
  on 
  to 
  the 
  more 
  highly 
  organised 
  

   forms 
  as 
  these 
  arose, 
  for 
  without 
  such 
  assimilative 
  power 
  they 
  could 
  not 
  

   survive 
  in 
  a 
  fresh 
  world 
  containing 
  no 
  ready-formed 
  organic 
  food. 
  

  

  Just 
  as 
  in 
  carbon 
  fixation, 
  at 
  a 
  certain 
  stage 
  in 
  evolution, 
  a 
  luxus 
  method 
  of 
  

   fixation 
  was 
  evolved 
  in 
  the 
  chloroplast 
  of 
  the 
  green 
  cell, 
  which 
  was 
  able 
  to 
  

   work 
  at 
  a 
  higher 
  velocity 
  and 
  use 
  longer 
  wave-lengths 
  of 
  light 
  than 
  the 
  

   simpler 
  inorganic 
  colloid 
  which 
  preceded 
  it, 
  so 
  in 
  the 
  case 
  of 
  nitrogen, 
  the 
  

   slow 
  union 
  of 
  nitrogen 
  and 
  oxygen 
  to 
  form 
  oxides 
  of 
  nitrogen, 
  induced 
  by 
  

   sunlight, 
  in 
  inorganic 
  systems, 
  became 
  replaced 
  by 
  more 
  rapid 
  transformers 
  in 
  

   the 
  unicellular 
  green 
  plant 
  ; 
  and 
  when 
  organic 
  matter 
  began 
  to 
  accumulate, 
  

   still 
  another 
  luxus 
  channel 
  was 
  opened 
  by 
  those 
  bacteria 
  and 
  other 
  unicellular 
  

   organisms 
  which 
  can 
  use 
  the 
  supply 
  of 
  energy 
  of 
  decaying 
  non-nitrogenous 
  

   matter 
  to 
  build 
  up 
  nitrogenous 
  compounds, 
  utilising 
  atmospheric 
  nitrogen 
  for 
  

   the 
  purpose. 
  Examples 
  of 
  such 
  cases 
  of 
  luxus 
  fixation 
  are 
  the 
  azoto-bacter 
  

   living 
  free 
  in 
  the 
  soil 
  and 
  the 
  nitrogen-fixing 
  bacteria 
  in 
  the 
  tubercles 
  of 
  the 
  

   rootlets 
  of 
  the 
  Leguminosae. 
  It 
  is 
  obvious, 
  however, 
  that 
  there 
  existed 
  no 
  

   decaying 
  organic 
  matter 
  at 
  the 
  first 
  dawn 
  of 
  the 
  organic, 
  and 
  that 
  Leguminosae 
  

   and 
  all 
  plants 
  living 
  in 
  symbiosis 
  with 
  nitrogen-fixing 
  organisms 
  are 
  late 
  

   creations 
  in 
  the 
  evolution 
  of 
  life. 
  

  

  Interesting 
  and 
  of 
  great 
  practical 
  importance 
  as 
  are 
  these 
  symbioses 
  of 
  a 
  

   carbon-fixing 
  organism 
  with 
  a 
  nitrogen-fixing 
  organism 
  subsisting 
  upon 
  it 
  or 
  

   upon 
  its 
  dead 
  products, 
  it 
  is 
  logically 
  quite 
  clear 
  that 
  they 
  cannot 
  have 
  formed 
  

   the 
  origination 
  of 
  life 
  and 
  are 
  only 
  by-paths 
  of 
  evolution. 
  One 
  of 
  the 
  

   earliest 
  organisms 
  must 
  have 
  possessed 
  the 
  dual 
  function 
  united 
  in 
  a 
  

   single 
  cell, 
  or 
  solution-aggregate, 
  of 
  fixing 
  both 
  carbon 
  and 
  nitrogen. 
  

   Approaching 
  the 
  subject 
  from 
  this 
  aspect, 
  we 
  have 
  examined 
  the 
  simplest 
  

   unicellular 
  alga?, 
  and 
  have 
  found 
  that 
  they 
  do 
  possess 
  this 
  dual 
  function. 
  

  

  