50    EFFECTS  OF  SOIL,  ETC.  ON  ACTIVE  PRINCIPLES  OF  PLANTS. 
Many  growers  have  informed  me  that  they  are  obliged  to  let 
their  crops  stand  until  the  supply  from  foreign  growers  is  ready 
for  the  markets ;  the  result  is,  that  in  many  cases  the  plants  are 
allowed  to  remain  some  time  after  flowering  before  the  officinal 
parts  are  collected ;  and  since  my  experiments  are  so  strongly 
opposed  to  such  practice  being  allowed,  it  has  suggested  itself 
to  me  that  a  plan  which  might  remedy  this  would  be  for 
pharmaceutists  to  insist  that  the  plants  should  be  supplied  with 
their  flowers,  which  would  serve  as  a  guarantee  for  the  perfec- 
tion of  their  condition. 
It  is  much  to  be  regretted  that  chemists,  in  determining  the 
constituents  of  a  plant,  have  overlooked  the  important  relation 
which  exists  between  the  assimilative  action  of  plants  and  the 
mineral  constituents  of  the  soil.  In  the  case  of  plant's  supplied 
with  highly  nitrogenized  manure,  I  have  always  found  a  much 
larger  proportion  of  phosphates  and  nitrates,  and  variable  pro- 
portions of  soda  salts ;  the  latter  can  only  be  considered  as 
arising  from  the  manure.  As  such  plants  invariably  yield  a 
greater  number  of  flowers,  the  analysis  of  the  parts  of  the  plant, 
if  allowed  to  perfect  its  flowers,  can  only  be  complete  when  the 
proportions  of  its  separate  parts  are  only  considered. 
I  met  with  a  most  singular  illustration  of  how  the  mineral  con- 
stituents of  a  plant  may  vary,  in  some  foxglove  plants,  which, 
in  order  to  facilitate  my  experiments,  were  transplanted  in  the 
early  spring.  These  plants  were  taken  from  a  wood  near  Wim- 
bledon, with  a  portion  of  the  soil  for  analysis.  The  soil  con- 
sisted principally  of  decayed  vegetable  matter,  and  yielded  on 
incineration  about  9  per  cent,  ashes,  of  which  7  per  cent,  was 
soluble  in  water  and  dilute  sulphuric  acid,  the  remaining  2  per 
cent,  consisted  almost  entirely  of  oxide  of  iron  and  silica.  The 
complete  analysis  of  these  soils  will  be  found  in  Appendix  A. 
The  incineration  of  the  leaves  and  stalks  yielded  about  4  per 
cent,  ashes  when  taken  from  the  soil  referred  to,  and,  after  re- 
moval to  a  slightly  manured  soil,  yielded  nearly  10  per  cent, 
ashes.  The  juice  extracted  from  the  leaves  in  July  gave  con- 
siderable quantities  of  phosphates,  nitrates,  and  chlorides,  with 
traces  of  sulphates.    I  analysed  at  the  same  time  the  juice  ex- 
