best  with  them,  by  observing  what  modes  have  been  suc-
cessful with  weU-known  plants  of  the  same  families  and
aflSnities  in  the  old  coim tries.  Of  many  of  them,  the
value  in  building,  and  the  various  mechanic  arts,  in  dye-
ing and  tanning,  and  as  furnishing  articles  of  food,  or
materials  for  medicine,  are  not  yet  known.  We  shall  be
likely  to  find  them  most  readily  by  looking  for  uses  simi-
lar to  what  are  loiown  to  belong  to  plants  most  analogous
to  them.  "  If  there  is,"  says  De  CandoUe,  "  a  coimtry
where  the  theory  of  analogy  between  forms  and  proper-
ties may  become  eminently  useful,  it  is  North  America,
which,  situated  in  the  same  latitude  as  Europe,  is  occu-
pied by  analogous  vegetation."

The  uses  of  the  natural  arrangement  in  abridging  the
labor  of  acquisition,  and  aiding  the  memory  of  the
learner,  are  most  important ;  and  its  advantages  to  culti-
vators, to  physicians,  —  to  all  who  are  seeking  to  enlarge
their  knowledge  of  the  useful  or  dangerous  properties  of
plants,  that  they  may  be  able  to  avail  themselves  of  the
one,  or  counteract  the  other,  to  gain  materials  for  the
arts,  or  remedies  or  antidotes  in  medicine, — are  too
many  to  enumerate,  and  too  obvious  to  be  further  in-
sisted upon.
In  the  Conspectus,  or  Distribution  into  Families  and
Genera,  I  have  attempted  to  offer  a  substitute,  so  far  as
the  plants  treated  of  in  this  Report  are  concerned,  for
the  arrangement  by  the  artificial  system.  This  attempt
I  submit  with  many  misgivings.  If  it  shall  be  considered
a  failure,  it  may  at  least  serve  to  aid  others  in  more  suc-
cessfully accomplishing  the  object.
