THE  ORIGIN  OF  FERMENTS. 
169 
coagulate.  It  remains  alkaline,  and  preserves,  I  would  venture 
to  say,  entirely  all  the  properties  of  fresh  milk.  Then  if,  into 
this  milk,  thus  retaining  its  integrity,  the  atmospheric  dusty 
particles  are  introduced,  it  changes  jand  coagulates,  and  the 
microscope  shows  the  existence  in  it  of  divers  animal  and  vege- 
table productions. 
It  would  be  very  interesting  to  ascertain  whether  the  fluids 
belonging  to  the  animal  economy,  such  as  milk  and  urine, 
contain  normally  or  accidentally,  previously  to  all  contact  with 
the  common  air,  the  germs  of  organized  productions.  This  is  a 
question  which  I  hope  to  resolve  in  a  subsequent  communica- 
tion. 
The  generally  admitted  theory  of  ferments,  and  that  which  of 
late  years  had  received  fresh  support  from  the  writings  or  the 
labors  of  various  chemists,  consequently  appears  to  be  more  and 
more  incongruous  with  experiment.  The  "  ferment"  is  not  a 
dead  substance,  without  determinate  specific  properties.  It  is 
a  being,  whose  germ  is  derived  from  air.  It  is  not  an  albu- 
minous substance,  altered  by  oxygen.  The  presence  of  albumi- 
nous matters  is  an  indispensable  condition  of  all  fermentation, 
because  the  "  ferment"  depends  upon  them  for  its  life.  They 
are  indispensable  in  the  light  of  an  aliment  to  the  ferment. 
The  contact  of  the  atmospheric  air  is,  primarily  equally  an  in- 
dispensable condition  of  fermentation,  but  it  is  so  in  virtue  of 
its  being  a  vehicle  of  the  germs  of  the  ferments." 
What  is  the  true  nature  of  these  germs  ?  Do  they  not 
require  oxygen,  in  order  to  pass  from  the  state  of  germs  to  that 
of  adult  ferments,  such  as  are  not  met  with  in  the  products  un- 
dergoing fermentation  ?  I  have  not  yet  arrived  at  any  fixed 
conclusion  with  respect  to  these  grave  questions.  I  am  en- 
deavoring to  pursue  the  inquiry  with  all  the  attention  it  merits; 
but  the  really  capital  difficulty  of  these  studies  consists  in  the 
isolated,  individual  protection  of  the  various  ferments.  I  may 
assert  that  there  are  a  great  many  distinct,  organized  ferments, 
which  excite  chemical  transformations,  varying  according  to  the 
nature  and  organization  of  the  ferment.  Bat  in  most  cases  the 
nutriment  suitable  to  some,  allows  of  the  development  of  others 
of  them,  whence  arise  the  most  complicated  and  the  most  variable 
phenomena.    If  we  could  only  isolate  one  of  these  ferments,  in 
