ON  THE  ORIGIN  OF  FERMENTS. 
167 
The  following  are  the  constant  results  of  the  experiments  so 
made. 
The  fluid  in  the  flask  which  has  received  the  amianthus  de- 
prived of  the  atmospheric  dust  remains  unaltered  at  the  tem- 
perature of  30^  C,  whatever  may  be  the  duration  of  its  exposure 
to  this  heat,  which  is  so  favorable  to  the  putrefaction  of  urine. 
On  the  contrary,  at  the  end  of  six  hours,  the  urine  which  has 
received  the  atmospheric  dust,  presents  organized  products — 
Mucedinea  or  Infusoria.  Among  the  latter  I  have  noticed 
chiefly  Bacteria^  very  minute,  Vibriones,  and  Monads,  in  fact, 
the  same  Infusoria  that  I  have  found  in  the  same  urine  exposed 
to  the  contact  of  the  atmospheric  air  at  a  temperature  of  30*^  C. 
During  the  following  days  will  be  witnessed  an  abundant  depo- 
sition of  crystals  of  ammoniaco-magnesian  phosphates  and  of 
the  alkaline  lithates.  The  urine  becomes  more  and  more  ammo- 
niacal.  Its  urea  disappears  under  the  influence  of  the  true 
ferment  of  the  urine,  a  ferment  which  I  have  proved  to  be 
organized,  and  whose  germ  could  only  have  been  introduced  in 
the  atmospheric  dust,  as  well  as  that  of  the  Infusoria  or  of  the 
Mucedinea. 
Milk  exhibits  still  more  interesting  properties.  I  have  said 
that,  before  filling  the  flask  with  air  which  has  been  subjected 
to  a  red  heat,  and  hermetically  closing  it,  I  caused  the  urine  to 
boil  for  two  or  three  minutes.  This  duration  of  the  ebullition 
is  sufficient,  and  everything  leads  me  to  believe  that  even  less 
careful  precautions  will  suffice  to  deprive  of  all  viability  the 
germs  which  may  have  fallen  into  the  urine  subsequent  to  its 
emission. 
This  being  granted,  let  us  repeat,  without  any  change,  the 
operation  above  described — now,  however,  not  upon  urine,  but 
upon  fresh  milk  ;  that  is  to  say,  after  this  fluid  has  been  boiled 
for  two  or  three  minutes,  and  the  flask  has  been  refilled  with  air 
heated  to  redness,  let  us  keep  it  closed  at  a  temperature  of 
30^  C. 
After  a  variable  lapse  of  time — generally  of  three  to  ten 
days — the  milk  in  all  the  flasks  thus  prepared  will  be  found 
coagulated.  Under  the  prevalent  views  respecting  the  phe- 
nomenon of  the  coagulation  of  milk,  there  is  nothing  in  this  cir- 
cumstance to  excite  surprise.    When  milk,  it  is  said,  is  exposed 
