534  Botanical  Characters  of  Officinal  Plants.  {^SZgfT* 
well  known.  It  is  also  the  case  with  the  cultivated  plum  compared 
with  the  harsh  sloe  of  our  hedges.  The  carrot  and  the  hemlock  are 
also  mentioned  among  the  exceptions  ;  but,  in  the  first  place,  it  must 
be  remembered  that  both  are  situated  near  the  boundaries  of  a  very  large 
order,  and  that  they  both  differ  materially  in  their  organic  structure* 
Conium  and  analogous  plants  contain  a  sap  which  is  absent  in  the  non- 
poisonous  Umbelliferae.  J.  Chatin  asserts  that  the  active  substance  is 
not  distributed  in  the  fruits  of  hemlock  in  the  same  manner  as  in  the 
other  Umbelliferae. 
If  plants  are  viewed  from  the  standpoint  of  their  chemical  composi- 
tion a  deduction  of  the  Linnaean  principle  is  obvious,  which,  when  their 
therapeutic  properties  were  studied,  seemed  inexplicable.  There  are 
analogies  of  the  characters  and  compositions  which  exist  between  allied 
families.  DeCandolle  says  in  regard  to  them  :  u  We  may  even  assume 
that  the  properties  of  certain  families  resembling  each  other  in  their 
organic  structure  are  similar  otherwise." 
To  make  this  part  of  the  question  explicit  a  truly  natural  botanic  clas- 
sification would  be  required,  /'.  one  that  would  indicate  the  origin  of 
the  various  Species,  Genera  and  Orders,  as  well  as  the  many  ties  which 
connect  them,  and  also  the  process  of  development  they  went  through. 
Such  a  classification  could  not  be  demonstrated  by  a  table,  but  instead 
a  geographical  chart,  as  it  were,  would  have  to  be  imagined,  with  the 
Species,  Genera  and  Families  arranged  in  such  a  manner  that  the  con- 
necting species  are  bounded  by  the  neighboring  families.  In  the  present 
condition  of  science  this  is  impossible  ;  nevertheless,  the  relation  of 
organization  existing  between  certain  families  may  be  taken  into  con- 
sideration. Let  us  see,  in  a  few  examples,  whether  the  active  prin- 
ciples attempt  to  intermingle  to  the  same  extent  as  the  physical  char- 
acters of  two  allied  families  do. 
We  will  begin  with  the  important  group  of  Rutacea.  Botanically, 
this  family  is  placed  among  the  Burseraceae,  Ochnaceae,  Ranunculaceae* 
and  Geraniaceae.  Its  relation  to  the  Burseraceae  is  established  by  the 
analogy  between  Ailanthus  and  Rhus.  As  we  approach  from  this  point 
we  find  that  to  the  resinous  constituents  of  the  Burseraceae  an  acrid 
volatile  substance  is  added  (Rhus  toxicodendron);  the  bitter  principle 
of  the  Rutaceae  disappears  and  is  replaced  by  acrid,  volatile  principles 
(Ailanthus  glandulosa).  Quassia  and  Picraena,  neighbors  of  Ochnacecey 
contain,  like  these,  bitter  substances.    According  to  Baillon,  the  Ran- 
