﻿Concerned 
  in 
  the 
  Decomposition 
  of 
  Glucose 
  and 
  Mannitol. 
  303 
  

  

  that 
  these 
  products 
  divide 
  themselves 
  into 
  two 
  groups 
  each 
  represented 
  by 
  

   two 
  curves 
  which 
  stand 
  in 
  complementary 
  relationship 
  to 
  one 
  another. 
  The 
  

   acetic 
  acid 
  curve 
  is 
  the 
  mirror 
  image 
  of 
  the 
  curve 
  for 
  alcohol, 
  and 
  the 
  succinic 
  

   acid 
  curve 
  is 
  roughly 
  the 
  reflection 
  of 
  the 
  curve 
  representing 
  total 
  carbon 
  

   dioxide 
  and 
  formic 
  acid. 
  In 
  fig. 
  2 
  the 
  succinic 
  acid 
  is 
  seen 
  to 
  rise 
  somewhat, 
  

   opposite 
  column 
  of 
  Experiment 
  1, 
  whereas 
  it 
  should 
  fall 
  in 
  correspondence 
  to 
  

   the 
  rise 
  in 
  the 
  carbonic 
  acid 
  curve, 
  but 
  reference 
  to 
  the 
  figures 
  for 
  the 
  total 
  

   products 
  in 
  this 
  experiment 
  (Table 
  IV) 
  will 
  show 
  that 
  in 
  this 
  one 
  case 
  they 
  

   totalled 
  to 
  over 
  a 
  hundred 
  per 
  cent., 
  due 
  probably 
  to 
  a 
  small 
  amount 
  of 
  

   acid 
  derived 
  from 
  the 
  nitrogenous 
  material 
  of 
  the 
  culture 
  medium. 
  The 
  

   important 
  fact, 
  however, 
  is 
  that 
  the 
  succinic 
  acid 
  belongs 
  to 
  a 
  group 
  of 
  

   substances 
  all 
  consisting 
  of 
  two 
  or 
  a 
  multiple 
  of 
  two 
  carbon 
  atoms, 
  viz., 
  

   succinic 
  acid, 
  acetic 
  acid 
  and 
  alcohol, 
  and 
  that 
  it 
  is 
  this 
  group 
  which 
  stands 
  

   in 
  complementary 
  relationship 
  to 
  the 
  group 
  containing 
  formic 
  acid 
  and 
  carbon 
  

   dioxide. 
  This 
  is 
  well 
  seen 
  from 
  fig. 
  3. 
  

  

  Summary 
  and 
  Conclusions 
  of 
  Part 
  IV. 
  

  

  (1) 
  Glucose 
  has 
  been 
  shown 
  to 
  break 
  down 
  under 
  the 
  influence 
  of 
  

   Bacterium 
  coli 
  into 
  three 
  main 
  groups 
  of 
  products 
  : 
  — 
  

  

  (1) 
  Lactic 
  acid. 
  

  

  (2) 
  Acetic 
  acid, 
  alcohol, 
  and 
  succinic 
  acid. 
  

  

  (3) 
  Carbon 
  dioxide, 
  hydrogen, 
  and 
  formic 
  acid. 
  

  

  There 
  is 
  a 
  closer 
  relationship 
  between 
  the 
  products 
  of 
  Groups 
  2 
  and 
  3 
  

   than 
  exists 
  between 
  either 
  group 
  and 
  Group 
  1. 
  The 
  reason 
  for 
  this 
  may 
  be 
  

   that 
  the 
  rate 
  at 
  which 
  the 
  substances 
  of 
  Group 
  2 
  are 
  formed 
  is 
  conditioned 
  by 
  

   the 
  availability 
  of 
  the 
  hydrogen 
  of 
  Group 
  3. 
  If 
  the 
  mother 
  substance 
  of 
  

   alcohol 
  and 
  acetic 
  acid 
  is 
  acetaldehyde, 
  it 
  is 
  easy 
  to 
  understand 
  that 
  the 
  rate 
  

   of 
  formation 
  of 
  this 
  substance 
  would 
  be 
  influenced 
  by 
  the 
  rate 
  at 
  which 
  part 
  

   of 
  it 
  was 
  reduced 
  to 
  alcohol 
  by 
  the 
  hydrogen 
  nascent 
  in 
  Group 
  3, 
  so 
  that 
  the 
  

   formation 
  of 
  the 
  products 
  of 
  the 
  last 
  two 
  groups 
  would 
  tend 
  to 
  keep 
  pace 
  

   with 
  one 
  another, 
  whereas 
  the 
  first 
  reaction, 
  of 
  which 
  the 
  end 
  product 
  is 
  

   lactic 
  acid, 
  being 
  independent 
  of 
  the 
  co-operation 
  of 
  hydrogen 
  for 
  its 
  

   formation, 
  would 
  run 
  a 
  course 
  quite 
  independent 
  of 
  the 
  other 
  reactions, 
  

   which, 
  as 
  a 
  matter 
  of 
  fact, 
  it 
  is 
  found 
  to 
  do. 
  

  

  It 
  was 
  shown 
  in 
  Parts 
  II 
  and 
  III 
  that 
  succinic 
  and 
  acetic 
  acid 
  were 
  

   closely 
  related 
  in 
  origin, 
  and 
  this 
  view 
  is 
  confirmed 
  by 
  the 
  present 
  result. 
  

   Moreover, 
  it 
  is 
  also 
  clear 
  that, 
  in 
  regard 
  to 
  the 
  interchangeability 
  of 
  these 
  

   two 
  products 
  of 
  the 
  fermentation, 
  the 
  availability 
  of 
  hydrogen 
  is 
  a 
  critical 
  

   factor. 
  If 
  there 
  is 
  no 
  available 
  hydrogen, 
  succinic 
  acid 
  would 
  be 
  formed, 
  

  

  