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ON  FERMENTATION. 
ON  FERMENTATION. 
By  M.  Pasteur. 
M.  Pasteur  has  extended  his  observations  of  the  characters 
of  amylic  alcohol,  and  of  the  crystallography  of  its  derivatives, 
to  the  investigation  of  the  phenomena  of  fermentation,  and  has 
arrived  at  results  which  he  believes  to  indicate  a  remarkable 
connexion  between  the  phenomena  of  fermentation  and  the 
characters  of  molecular  dissymetry  of  organic  substances. 
He  treats  first  of  that  kind  of  fermentation  which  gives  rise 
to  the  production  of  lactic  acid.  This  is  known  to  take  place 
when  a  solution  of  sugar,  mixed  with  chalk,  for  the  purpose  of 
keeping  the  liquid  neutral,  is  brought  in  contact  with  nitrogen- 
ous substances,  such  as  casein,  gluten,  animal  membrane,  &c. 
The  essential  nature  of  this  phenomenon  is,  however,  very 
obscure ;  the  special  influence  of  the  nitrogenous  substance  is 
altogether  unknown.  Its  mass  is  not  sensibly  diminished.  It 
does  not  necessarily  become  putrid.  Nevertheless,  it  undergoes 
a  progressive  alteration,  although  it  is  difficult  to  say  in  what 
this  alteration  may  consist. 
Previous  investigations  have  not  led  to  the  detection  of  the 
development  of  vital  organisms  during  the  lactic  acid  fermenta- 
tion, otherwise  than  accidentally,  and  without  any  intimate  con- 
nexion with  the  process  itself. 
These  facts  appear,  therefore,  to  bear  out  the  views  of  Pro- 
fessor Liebig,  who  regards  a  ferment  as  a  substance  eminently 
susceptible  of  change,  and  capable,  while  undergoing  decompo- 
sition, of  exciting  fermentation  of  a  substance  with  which  it  is 
in  contact,  as  a  consequence  of  its  own  alteration,  by  disturbing 
the  molecular  constitution  of  the  fermentible  substance.  Accord- 
ing to  Professor  Liebig,  this  is  the  primary  cause  of  all  kinds  of 
fermentation,  and  also  the  origin  of  most  contagious  diseases. 
This  view  has  gradually  gained  recognition,  and  has  been 
maintained  in  the  memoirs  written  on  the  subject  by  MM.  Fremy 
and  Boutron,  M.  Gerhardt,  and  quite  recently,  by  M.  Berthelot. 
The  investigations  of  these  chemists  all  agree  in  tending  to  dis- 
credit the  influence,  in  any  way,  of  organization  and  vitality,  as 
the  cause  of  the  phenomena  of  fermentation. 
M.  Pasteur  has,  however,  been  induced  to  adopt  an  entirely 
