AmNovl'imaiin-}^nt  Groups,  their  Constituents  and  Properties.  547 
and  German  refer  to  the  shape  of  the  leaves  and  the  hold 
which  they  were  supposed  to  have  upon  the  heart  by  means  of 
their  divisions.  The  generic  name  Panax  is  intended  to  indicate 
the  value  as  a  panacea  attributed  to  the  root  from  its  supposed 
resemblance  to  the  figure  of  a  man  ;  the  same  cause  for  which 
miraculous  virtues  were  ascribed  to  the  European  mandragora  root, 
though  neither  the  Latin  name  of  the  latter  nor  its  vernacular 
synonyms  remind  us  of  the  high  esteem  in  which  it  was  formerly 
held  as  a  remedy. 
The  relation  between  genetic  form  and  properties,  to  which  I 
have  referred,  rests  upon  more  substantial  ground  than  the  illogical 
conclusions  deduced  from  mere  physical  appearance.  It  is  based 
upon  the  axiom  that  a  like  cause  must  produce  a  like  effect ;  the  cause 
— though  at  present  it  can  only  be  conjectured  without  having 
adequate  proof — will  doubtless  ultimately  be  ascertained  to  operate 
in  the  interior  fabric  of  the  plant.  While  in  such  plants,  frequently, 
the  external  organs  show  undoubted  evidence  of  close  relationship, 
these  latter  do  not  constitute  the  moving  cause,  but  are  of  secondary 
significance,  though  they  may  sometimes  embrace  all  the  members 
identical  or  at  least  closely  analogous  in  their  internal  structure. 
For  these  reasons,  the  groups  of  plants  agreeing,  substantially,  in 
their  constituents,  and  hence  in  their  effects,  must  vary  in  extent, 
and  cannot  be  absolutely  identical  with  those  groups  which  by  sys- 
tematic botany  have  been  established  under  the  designation  of 
tribes,  families  or  orders.  Several  of  these  latter  may  sometimes 
agree  in  the  presence  of  one  important  constituent ;  but  more  fre- 
quently it  will  be  found  that  one  order,  particularly  if  embracing 
numerous  genera  and  species,  may  be  regarded  as  forming  two  or 
more  groups,  the  members  of  each  having  a  close  family  resemblance 
in  the  products  furnished  by  them,  and,  as  far  as  known,  in  their 
anatomy. 
Starch  is  a  compound  generated  in  nearly  all  chlorophyll-forming 
plants,  and  the  storage  material,  common  to  by  far  the  largest  num- 
ber of  seed-bearing  plants,  especially  to  the  subterraneous  organs 
of  the  biennial  or  perennial  herbs.  Yet  it  is  almost  entirely  absent 
from  the  extensive  order  of  Composite — which  alone  embraces  over 
10,000  known  species — being  replaced  by  the  analogous  carbo- 
hydrate inulin,  and  this  is  also  a  constituent  of  Campanulaceae 
Lobeliaceae  and  one  or  two  botanically  allied  orders. 
