﻿Studies 
  of 
  Photo- 
  synthesis 
  in 
  Fresh-water 
  Algce. 
  211 
  

  

  promising, 
  namely, 
  Can 
  these 
  simple 
  organic 
  substances 
  act 
  as 
  nutrients 
  for 
  

   cells 
  ? 
  If 
  formaldehyde 
  be 
  the 
  primary 
  stage 
  in 
  photo-synthesis 
  by 
  which 
  

   green 
  cells 
  are 
  nourished, 
  then 
  it 
  ought 
  to 
  be 
  possible 
  by 
  supplying 
  form- 
  

   aldehyde 
  when 
  carbon 
  dioxide 
  is 
  shut 
  off 
  to 
  make 
  green 
  cells 
  grow 
  and 
  

   flourish. 
  

  

  Many 
  attempts 
  have 
  been 
  made 
  in 
  this 
  direction, 
  but 
  have 
  all 
  failed, 
  or 
  

   given 
  very 
  dubious 
  results, 
  because 
  of 
  the 
  highly 
  poisonous 
  action 
  of 
  form- 
  

   aldehyde. 
  Formaldehyde, 
  if 
  and 
  when 
  formed 
  in 
  a 
  green 
  cell, 
  must 
  imme- 
  

   diately 
  be 
  condensed 
  into 
  a 
  sugar 
  or 
  some 
  other 
  non-poisonous 
  organic 
  

   compound 
  or 
  the 
  cell 
  will 
  perish 
  ; 
  there 
  is, 
  accordingly, 
  no 
  demonstrable 
  

   amount 
  of 
  formaldehyde 
  in 
  the 
  cell. 
  If 
  now 
  it 
  be 
  supposed 
  that 
  the 
  cell 
  in 
  

   sunlight 
  is 
  always 
  producing 
  formaldehyde 
  which 
  at 
  once 
  is 
  changed 
  into 
  

   something 
  else, 
  then 
  in 
  order 
  to 
  mimic 
  this 
  process 
  experimentally 
  a 
  system 
  

   must 
  be 
  invented 
  in 
  which 
  formaldehyde 
  at 
  minute 
  concentrations 
  is 
  fed 
  in 
  

   slowly, 
  at 
  a 
  rate 
  not 
  greater 
  than 
  the 
  cells 
  of 
  the 
  system 
  can 
  assimilate 
  it. 
  

   The 
  formaldehyde 
  must 
  not 
  be 
  added 
  to 
  the 
  solution 
  in 
  which 
  the 
  cells 
  are 
  

   growing 
  at 
  the 
  outset, 
  for 
  any 
  quantity 
  detectable 
  afterwards 
  by 
  increase 
  in 
  

   the 
  cells 
  would 
  kill 
  them. 
  It 
  must 
  be 
  continuously 
  and 
  very 
  slowly 
  

   administered 
  as 
  a 
  dilute 
  vapour. 
  

  

  Two 
  glass 
  tubes 
  of 
  about 
  - 
  5 
  cm. 
  in 
  diameter, 
  each 
  about 
  18 
  cm. 
  long, 
  were 
  

   sealed 
  at 
  the 
  one 
  end 
  so 
  as 
  to 
  make 
  narrow 
  test-tubes. 
  One 
  of 
  these 
  was 
  

   about 
  half 
  filled 
  with 
  formol 
  (40 
  per 
  cent, 
  formaldehyde), 
  the 
  other 
  with 
  

   methylic 
  alcohol. 
  The 
  tube 
  containing 
  formol 
  was 
  placed 
  slanting 
  in 
  bottle 
  

   No. 
  9, 
  the 
  closed 
  end 
  resting 
  on 
  the 
  bottom 
  of 
  the 
  bottle, 
  and 
  the 
  upper 
  

   end 
  on 
  the 
  inside 
  of 
  the 
  neck 
  close 
  beneath 
  the 
  glass 
  lid. 
  The 
  tube 
  con- 
  

   taining 
  methylic 
  alcohol 
  was 
  similarly 
  placed 
  in 
  No. 
  11. 
  Both 
  glass 
  lids 
  

   were 
  tightly 
  screwed 
  down 
  to 
  exclude 
  atmospheric 
  carbon 
  dioxide. 
  The 
  

   nutrient 
  solutions 
  contained 
  nitrite 
  as 
  well 
  as 
  phosphate. 
  The 
  two 
  flasks 
  

   were 
  kept 
  exposed 
  to 
  light, 
  and 
  after 
  some 
  weeks 
  there 
  were 
  good 
  growths 
  

   obtained 
  in 
  both. 
  

  

  Judged 
  from 
  the 
  amounts 
  of 
  nitrogen 
  there 
  was 
  a 
  fixation 
  of 
  3 
  - 
  5 
  mgrm. 
  in 
  

   the 
  formaldehyde 
  nutrition, 
  and 
  a 
  fixation 
  of 
  7'1 
  mgrm. 
  in 
  the 
  methylic 
  

   alcohol 
  nutrition. 
  To 
  get 
  from 
  the 
  nitrogen 
  fixation 
  to 
  the 
  carbon 
  fixation 
  

   these 
  figures 
  must 
  be 
  multiplied 
  by 
  a 
  factor 
  of 
  at 
  least 
  8, 
  for 
  the 
  weight 
  of 
  

   carbon 
  even 
  in 
  protein 
  is 
  treble 
  that 
  of 
  the 
  nitrogen, 
  and 
  there 
  is 
  carbon 
  but 
  

   no 
  nitrogen 
  in 
  carbohydrates 
  and 
  fats. 
  If 
  this 
  factor 
  be 
  applied 
  there 
  is 
  a 
  

   fixation 
  of 
  28 
  mgrm. 
  of 
  carbon 
  from 
  formaldehyde 
  (=70 
  mgrm. 
  of 
  formalde- 
  

   hyde), 
  and 
  of 
  56"8 
  mgrm. 
  of 
  carbon 
  from 
  methylic 
  alcohol 
  (= 
  151 
  mgrm. 
  of 
  

   methylic 
  alcohol). 
  The 
  bottles 
  Nos. 
  10 
  and 
  12 
  were 
  a 
  similarly 
  conducted 
  

   experiment, 
  but 
  without 
  available 
  nitrates 
  or 
  other 
  easily 
  assimilable 
  

  

  