CULTIVATION  OF  CINCHONA  PLANTS  UNDER  GLASS.  259 
dried  specimens,  the  great  variety  of  structure  and  characteristic 
peculiarities  which  the  leaves  present ;  but  when  once  well  ob- 
served, the  aspect  of  the  plant  fixes  itself  in  the  memory. 
The  respiration  of  plants,  as  affected  by  a  too  retentive  soil  or 
by  too  abundant  application  of  water  to  the  roots,  has  to  be 
studied,  and  it  is  also  necessary  to  mark  the  period  of  hiberna- 
tion or  repose,  and  to  encourage  rather  than  to  interfere  with 
rest  at  this  period,  a  period  which  seems  in  India  to  be  very  ac- 
curately marked,  and  which  even  under  glass,  it  is  not  difficult 
to  trace. 
Then  the  nutrition  of  the  plants  will  require  much  care.  It 
may,  at  first  sight,  seem  requisite  simply  to  provide  the  needed 
soil ;  and  very  pure  sand,  such  as  Reigate  sand,  rich  loam,  and 
bog  earth,  in  proportions,  varying  according  to  the  species, — 
when  mixed,  as  I  find  desirable,  with  broken  brick, — will  suffi- 
ciently afford  this.  But  there  is  more  than  this  ;  for  we  shall 
find,  if  we  study  the  plant,  that  it  is  desirable  to  supply  it  at  the 
period  of  its  most  active  vegetation  with  food  ministered,  as., 
much  as  possible,  in  a  liquid  form,  and  therefore  more  easily  as., 
gimilated.  For  as  regards  the  life  and  growth  of  the  plant,  we 
may,  in  a  certain  sense,  adopt  the  saying  of  Thales,  that  '^  all 
things  are  from  water,"  for  all  things  must  be  in  solution  (either 
aqueous  or  aerial)  before  they  can  be  changed  into  the  living 
substance  of  the  vegetable.  Now  the  natural  solvent  is-  rain  as 
it  falls  from  the  clouds,  and  in  the  normal  state  (as  observed  by 
Weddell  and  Markham)  of  the  Cinchonce^^  the  roots  spread 
superficially  through  a  loose  mass  of  earth  and  decaying  vegeta- 
tion, amidst  which  they  absorb,  together  with,  the  rain-water, 
various  mineral  substances,  and  also  gases,  especially  carbonic 
acid,  presented  to  the  spongioles  in  the  manner  most  to  their 
advantage. 
M.  H.  Struvef  has  recently  demonstrated  the  existence,  under 
certain  conditions,  of  nitrite  of  ammonia,  together  with  ozone 
and  oxygenated  water  in  rain  and  snow ;  and  M,  Deville  has 
found  in  snow  and  rain,  collected  in  the  neighborhood  of  the 
*The  C  succiruhra  prefers  a  stronger  soil,  and,  perhaps  on  this  ac- 
count, is  more  easy  to  cultivate  than  som.e  others.. 
t  *•  Journal  de  Pharmacie  et  de  Chimie,"  November,  1869,  p.  357. 
