250 
ON  THE  PREPARATION  OF  EXTRACTS. 
plant  instead  of  the  leaf  only  ;  second,  the  plant  being  cultivated 
instead  of  wild. 
The  first  cause  was  not  assigned  without  consideration  aided 
by  experiment. 
I  judged  that  the  juices  of  a  young  herbaceous  plant  were  not 
likely  to  be  similar  in  every  part  of  it  (thus  differing  from  a 
gentleman  who  spoke  on  this  subject  at  the  meeting),  but  that 
the  juice  of  the  stem  and  branches  would  in  all  probability 
mainly  consist  of  a  watery  solution  of  the  inorganic  food  of  the 
plant  on  its  way  to  the  leaves  for  elaboration  and  fixation,  and 
of  gummy,  albuminous  and  other  inert  matters  contained  in  the 
stem  ;  that  as  the  plant  grew  older  and  commenced  forming  its 
seed,  a  portion  of  such  elaborated  food  would  proceed  in  that 
direction,  and  be  found  in  transitu  in  the  softer  part  of  the  stem 
above  the  leaves.  In  the  case  of  plants  which  form  fleshy  roots, 
tubers,  etc.,  the  course  of  the  sap  would  be  also  diverted  down- 
wards through  the  stem,  in  all  cases  carrying  with  it  the  active 
principles  of  the  plant,  where  such  active  principles  are  found 
in  the  fruit,  or  root,  or  both.  Only  in  those  cases  therefore 
where  the  active  principles  of  the  plant  are  eventually  more  or 
less  completely  collected  in  the  root,  should  I  be  prepared  to  find 
the  juice  of  the  stem  rival  in  activity  that  of  the  leaves. 
Hyoscyamus  niger  is  not  one  of  those  cases.  I  therefore  made 
the  experiment  of  treating  in  a  precisely  similar  manner,  equal 
portions,  twenty  ounces,  of  rejected  stems,  and  of  leaves  and 
tops  such  as  I  always  employ  for  extracts.  I  may  here  state 
probably  I  reject  on  an  average  two-fifths  of  the  plant ;  the  indi- 
vidual proportions  however  are  very  wide  of  the  average. 
The  stems  yielded  5i  dr.  of  a  pale  green  extract,  very  saline 
in  taste  and  less  bitter  and  odorous  than  the  9i  dr.  of  dark  ex- 
tract I  obtained  from  the  leaves.  The  pale  green  extract  was 
so  evidently  inferior  that  the  physiological  test  was  not  resorted 
to. 
The  mixture  of  the  poor  and  saline  extract  of  the  stem  with 
the  rich  and  characteristic  extract  of  the  leaves,  in  my  opinion 
accounted  for  much  of  the  inferiority  of  purchased  specimens.  I 
therefore  put  by  specimens  of  both  extracts  and  of  their  mix- 
ture, for  the  purpose  of  illustrating  a  paper  I  intended  sending  to 
the  Society  ;  but,  having  first  prudently  consulted  the  old  Jour- 
