Bichat's  studies  related  to  Man  alone ;  and  his  method  of  com-
parison bore  only  upon  the  simplest  and  most  restricted  cases  of
all ;  the  comparison  of  parts  and  that  of  ages.     His  principle  must,


ELEMENTS   AND   PRODUCTS.  ^37

therefore,  necessarily  undergo  some  transformations,  to  fit  it  fo'  a
more  extensive  application.  The  most  important  of  these  improve-
ments, especially  in  a  logical  view,  appears  to  me  to  consist  in
the  great  distinction  introduced  by  M.  de  Blainville  be-  Elements  nn.i
tween  the  true  anatomical  elements  and  the  simple  pi-o'J™"-
products  of  the  organism,  which  Bichat  had  confounded.  We  saw
before  the  importance  of  this  distinction  in  the  chemical  study  of
organic  substances :  and  we  meet  it  agaih  now,  face  to  face,  as  an
anatomical  conception.
