﻿Studies 
  of 
  Photo-synthesis 
  in 
  Fresh-water 
  Algce. 
  215 
  

  

  6. 
  The 
  earliest 
  products 
  of 
  photo-synthesis, 
  such 
  as 
  formaldehyde 
  and 
  

   methylic 
  alcohol, 
  are 
  highly 
  poisonous 
  to 
  the 
  green 
  cell 
  ; 
  but 
  fed 
  to 
  it 
  at 
  

   sufficiently 
  high 
  dilution, 
  can 
  be 
  used 
  as 
  nutrition 
  in 
  absence 
  of 
  carbon 
  

   dioxide, 
  and 
  very 
  marked 
  growths 
  have 
  been 
  obtained 
  with 
  these 
  substances 
  

   as 
  the 
  sole 
  source 
  of 
  carbon. 
  

  

  7. 
  In 
  the 
  absence 
  of 
  all 
  other 
  sources 
  of 
  nitrogen 
  save 
  the 
  elemental 
  

   nitrogen 
  of 
  the 
  atmosphere, 
  but 
  with 
  abundance 
  of 
  carbon 
  dioxide, 
  the 
  

   unicellular 
  algae 
  can 
  fix 
  nitrogen, 
  grow 
  and 
  form 
  proteins. 
  

  

  8. 
  The 
  rate 
  of 
  fixation 
  and 
  growth 
  is, 
  however, 
  greatly 
  accelerated 
  if 
  nitrites 
  

   or 
  oxides 
  of 
  nitrogen 
  are 
  available. 
  

  

  9. 
  These 
  oxides 
  of 
  nitrogen 
  can 
  be 
  supplied 
  in 
  gaseous 
  form 
  from 
  the 
  

   amosphere, 
  and 
  pure 
  country 
  air 
  normally 
  contains 
  such 
  oxides 
  of 
  nitrogen, 
  

   especially 
  in 
  spring 
  and 
  summer. 
  

  

  REFERENCES. 
  

  

  (1) 
  JamiesoD, 
  ' 
  Reports 
  Agricultural 
  Research 
  Association,' 
  Aberdeen, 
  1905-1911. 
  

  

  (2) 
  Mameli 
  and 
  Pollacci, 
  " 
  Sull' 
  Assimilazione 
  dell' 
  Azoto 
  atmosferico 
  nei 
  Vegetali," 
  

  

  Pavia, 
  ' 
  Atti. 
  1st. 
  Bot.,' 
  vol. 
  14, 
  pp. 
  159-257 
  (1911). 
  

  

  (3) 
  Moore 
  and 
  Webster, 
  " 
  Synthesis 
  by 
  Sunlight 
  in 
  relation 
  to 
  the 
  Origin 
  of 
  Life 
  — 
  

  

  Synthesis 
  of 
  Formaldehyde, 
  etc.," 
  'Roy. 
  Soc. 
  Proc.,' 
  B, 
  vol. 
  87, 
  pp. 
  163-176 
  

   (1913). 
  

  

  (4) 
  Moore 
  and 
  Webster, 
  " 
  Action 
  of 
  Light 
  Rays 
  on 
  Organic 
  Compounds, 
  etc.," 
  ' 
  Roy. 
  Soc. 
  

  

  Proc.,' 
  B, 
  vol. 
  90, 
  pp. 
  168-186 
  (1919). 
  

  

  