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  The 
  Enzymes 
  of 
  B. 
  Coli 
  Communis 
  which 
  are 
  Concerned 
  in 
  the 
  

   Decomposition 
  of 
  Glucose 
  and 
  Mannitol. 
  Part 
  IV. 
  — 
  The 
  

   Fermentation 
  of 
  Glucose 
  in 
  the 
  Presence 
  of 
  Formic 
  Acid. 
  

   By 
  Egbrton 
  Charles 
  Grey 
  (John 
  Foulerton 
  Student). 
  

   (From 
  the 
  Biochemical 
  Laboratory, 
  Cambridge.) 
  

   (Communicated 
  by 
  F. 
  Gowland 
  Hopkins, 
  F.R.S. 
  — 
  Received 
  May 
  3, 
  1920.) 
  

  

  In 
  this 
  series 
  of 
  communications 
  the 
  writer 
  is 
  endeavouring 
  to 
  show 
  how, 
  

   by 
  varying 
  the 
  conditions 
  of 
  the 
  experiment, 
  it 
  is 
  possible 
  to 
  alter 
  the 
  pro- 
  

   portion 
  between 
  the 
  products 
  which 
  arise 
  from 
  the 
  fermentation 
  of 
  glucose 
  

   and 
  allied 
  substances, 
  and 
  to 
  point 
  out 
  how, 
  by 
  a 
  consideration 
  of 
  the 
  

   manner 
  in 
  which 
  these 
  products 
  group 
  themselves, 
  conclusions 
  may 
  be 
  

   drawn 
  as 
  to 
  the 
  order 
  in 
  which 
  such 
  products 
  arise 
  during 
  the 
  degradation 
  

   of 
  the 
  glucose 
  molecule. 
  Substances 
  which 
  can 
  be 
  shown 
  to 
  arise 
  in 
  constant 
  

   proportions 
  under 
  varying 
  conditions 
  of 
  experiment 
  may 
  be 
  considered 
  as 
  

   being 
  produced 
  by 
  one 
  and 
  the 
  same 
  enzyme. 
  

  

  In 
  Parts 
  II 
  and 
  III 
  it 
  was 
  shown 
  that 
  the 
  formation 
  of 
  lactic 
  acid 
  by 
  

   B. 
  coli 
  communis 
  ran 
  a 
  separate 
  course 
  to 
  that 
  of 
  the 
  other 
  products, 
  so 
  that 
  

   it 
  may 
  be 
  regarded 
  as 
  being 
  produced 
  by 
  a 
  separate 
  enzyme, 
  but 
  the 
  other 
  

   products 
  of 
  the 
  fermentation, 
  viz., 
  succinic 
  acid, 
  acetic 
  acid, 
  formic 
  acid, 
  and 
  

   alcohol, 
  together 
  with 
  the 
  gaseous 
  products 
  of 
  the 
  decomposition 
  of 
  formic 
  

   acid, 
  i.e., 
  carbon 
  dioxide 
  and 
  hydrogen, 
  all 
  appeared 
  to 
  be 
  grouped 
  together 
  

   and 
  to 
  form 
  an 
  alternative 
  course 
  for 
  the 
  decomposition 
  of 
  the 
  glucose. 
  

  

  In 
  the 
  present 
  communication 
  it 
  will 
  be 
  shown 
  that 
  this 
  group 
  of 
  products 
  

   must 
  be 
  subdivided 
  into 
  two 
  groups, 
  the 
  one 
  containing 
  formic 
  acid 
  and 
  its 
  

   gaseous 
  products 
  carbon 
  dioxide 
  and 
  hydrogen, 
  and 
  the 
  other 
  alcohol, 
  

   succinic 
  acid, 
  and 
  acetic 
  acid. 
  

  

  The 
  possibility 
  of 
  demonstrating 
  the 
  independence 
  of 
  formic 
  acid 
  on 
  the 
  

   one 
  hand 
  and 
  acetic 
  acid, 
  alcohol, 
  and 
  succinic 
  acid 
  on 
  the 
  other, 
  depends 
  on 
  

   finding 
  a 
  means 
  of 
  destroying 
  the 
  normal 
  balance 
  between 
  these 
  products. 
  

   It 
  is 
  probable 
  that 
  this 
  balance 
  is 
  conditioned 
  by 
  the 
  hydrogen 
  which 
  arises 
  

   through 
  the 
  decomposition 
  of 
  the 
  formic 
  acid, 
  for 
  this 
  hydrogen 
  might 
  reduce 
  

   acetaldehyde 
  to 
  alcohol, 
  and 
  in 
  this 
  way 
  the 
  formation 
  of 
  formic 
  acid 
  and 
  

   alcohol 
  would 
  tend 
  to 
  keep 
  pace 
  with 
  each 
  other. 
  However 
  this 
  may 
  be, 
  it 
  

   is 
  not 
  difficult 
  to 
  upset 
  this 
  balance, 
  and 
  one 
  method 
  of 
  so 
  doing 
  is 
  to 
  ferment 
  

   the 
  glucose 
  in 
  the 
  presence 
  of 
  added 
  formic 
  acid 
  in 
  the 
  form 
  of 
  calcium 
  

   formate. 
  How 
  the 
  added 
  formate 
  is 
  able 
  to 
  upset 
  the 
  normal 
  balance 
  which 
  

   exists 
  between 
  the 
  products 
  of 
  this 
  group, 
  the 
  writer 
  is 
  not 
  prepared 
  to 
  say. 
  

  

  