﻿242 
  ANNUAL 
  EEPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1929 
  

  

  by 
  means 
  of 
  ultra-violet 
  light. 
  As 
  so 
  often 
  happens 
  the 
  explanation 
  

   when 
  found 
  is 
  very 
  simple. 
  The 
  great 
  amount 
  of 
  energy 
  required 
  to 
  

   convert 
  the 
  carbonic 
  acid 
  into 
  carbohydrates 
  is 
  supplied 
  to 
  it 
  in 
  two 
  

   portions, 
  one 
  by 
  the 
  surface 
  and 
  the 
  other 
  by 
  the 
  visible 
  light. 
  

  

  Nothing 
  has 
  as 
  yet 
  been 
  said 
  of 
  the 
  actual 
  carbohydrates 
  which 
  

   have 
  been 
  photosynthesized 
  in 
  the 
  laboratory. 
  Although 
  as 
  yet 
  our 
  

   information 
  is 
  still 
  meager, 
  there 
  is 
  no 
  doubt 
  that 
  the 
  photosynthetic 
  

   sirup 
  is 
  a 
  mixture 
  containing 
  glucose 
  or 
  fructose, 
  or 
  both. 
  There 
  

   are 
  also 
  present 
  more 
  complex 
  carbohydrates, 
  which 
  can 
  be 
  resolved 
  

   to 
  the 
  simple 
  sugars 
  by 
  the 
  action 
  of 
  dilute 
  acid. 
  The 
  analogy 
  with 
  

   the 
  products 
  of 
  natural 
  photosynthesis 
  is 
  too 
  close 
  to 
  be 
  passed 
  by 
  

   without 
  comment. 
  

  

  Although 
  it 
  has 
  not 
  as 
  yet 
  been 
  possible 
  to 
  carry 
  out 
  a 
  complete 
  

   analysis 
  of 
  this 
  sirup, 
  owing 
  to 
  the 
  difficulty 
  of 
  preparing 
  a 
  sufficiently 
  

   large 
  amount, 
  interesting 
  information 
  has 
  been 
  gained 
  from 
  the 
  

   investigation 
  of 
  the 
  sugar 
  sirup 
  obtained 
  by 
  the 
  action 
  of 
  light 
  upon 
  

   formaldehyde 
  solution. 
  This 
  has 
  been 
  pursued 
  during 
  the 
  last 
  three 
  

   years. 
  We 
  owe 
  a 
  debt 
  of 
  gratitude 
  to 
  Sir 
  James 
  Irvine 
  for 
  the 
  

   signal 
  help 
  he 
  has 
  given 
  us 
  in 
  this 
  work. 
  He 
  himself 
  was 
  the 
  first, 
  

   in 
  association 
  with 
  Doctor 
  Francis, 
  to 
  prove 
  that 
  glucose 
  is 
  one 
  of 
  the 
  

   substances 
  actually 
  produced. 
  By 
  oxidation 
  of 
  the 
  sugars 
  to 
  the 
  

   acids 
  by 
  means 
  of 
  bromine, 
  and 
  the 
  crystallization 
  of 
  the 
  salts 
  of 
  

   these 
  with 
  brucine, 
  cinchonine, 
  and 
  quinine, 
  we 
  have 
  obtained 
  

   d-gluconic 
  and 
  also 
  d-erythronic 
  acids. 
  This 
  not 
  only 
  confirms 
  

   Irvine 
  and 
  Francis 
  in 
  their 
  proof 
  of 
  glucose, 
  but 
  it 
  also 
  proves 
  that 
  

   fructose 
  is 
  formed 
  just 
  as 
  in 
  the 
  living 
  plant. 
  In 
  addition 
  to 
  that, 
  

   there 
  is 
  produced 
  a 
  mixture 
  of 
  complex 
  acids 
  which 
  afford 
  convincing 
  

   evidence 
  of 
  the 
  synthesis 
  of 
  complex 
  carbohydrates. 
  

  

  Although 
  it 
  may 
  be 
  thought 
  that 
  the 
  use 
  of 
  formaldehyde 
  as 
  the 
  

   starting 
  "point 
  takes 
  away 
  something 
  from 
  the 
  interest, 
  yet 
  it 
  must 
  be 
  

   remembered 
  that 
  it 
  makes 
  but 
  little 
  difi^erence 
  whether 
  in 
  actual 
  fact 
  

   we 
  start 
  from 
  carbonic 
  acid 
  or 
  formaldehyde. 
  Without 
  doubt 
  the 
  

   first 
  substance, 
  transiently 
  formed 
  in 
  either 
  case, 
  is 
  the 
  same, 
  namely, 
  

   activated 
  formaldehj^de 
  which 
  polymerizes 
  to 
  the 
  sugars. 
  

  

  The 
  similarity 
  between 
  the 
  vital 
  and 
  the 
  laboratory 
  processes 
  is 
  

   not 
  confined 
  to 
  the 
  fact 
  that 
  the 
  products 
  from 
  the 
  two 
  are 
  the 
  same. 
  

   Botanists 
  tell 
  us 
  that 
  in 
  the 
  living 
  plant 
  the 
  photosynthesis 
  takes 
  

   place 
  on 
  a 
  surface, 
  so 
  also 
  is 
  a 
  surface 
  necessary 
  in 
  the 
  laboratory. 
  

   It 
  has 
  been 
  found 
  possible 
  to 
  compare 
  the 
  quantities 
  of 
  carbohydrates 
  

   synthesized 
  for 
  equal 
  areas 
  exposed 
  to 
  light 
  in 
  the 
  case 
  of 
  living 
  

   leaves 
  and 
  the 
  glass 
  vessels 
  of 
  the 
  laboratory. 
  These 
  quantities 
  are 
  

   about 
  the 
  same. 
  Some 
  plants 
  produce 
  more 
  and 
  other 
  produce 
  less 
  

   than 
  we 
  are 
  able 
  to 
  synthesize. 
  This 
  similarity 
  may 
  be 
  emphasized, 
  

   because 
  surely 
  Dame 
  Nature 
  in 
  the 
  living 
  leaf 
  has 
  produced 
  the 
  best 
  

   machine 
  she 
  could 
  for 
  her 
  purpose 
  of 
  food 
  production 
  for 
  her 
  children 
  

   of 
  the 
  vegetable 
  kingdom. 
  

  

  