Indicane,*  C^H^NC  •  O 'CeHijOj,  is  the  name  given  to  a
glucoside  which  occurs  not  only  in  Indigofera  anil,  I.  arrecta,
I.  tinctoria,  and  /.  sumatrana,  but  also  in  other  plants,  such  as
Isatis  tinctoria,  Polygonum  tinctorimn,  species  of  Phajus  and
other  orchids,  e.g.  Calanthe  and  Strobilanthes.  In  the  plant,
indicane  is  well  distributed  in  the  aerial  organs.  Thus  in  Indi-
gofera, it  is  found  in  all  the  tissues  of  the  leaf  except  the
tracheae  of  the  xylem,  it  is  also  abundant  in  the  apex  of  the
stem  in  all  tissues  except  the  wood  vessels  and  the  laticiferous
system.  The  flowers  also  have  a  small  quantity,  but  the  root
is  characterized  by  its  absence. f

At  one  time  it  was  considered  that  the  chloroplasts  played
an  important  direct  part  in  the  formation  of  indicane,  but  Leake
can  find  no  evidence  of  this.
Identification.
1.  The  tissue  may  be  boiled  in  a  2  per  cent  solution  of
ammonia.  The  addition  of  chloroform  to  the  filtered  extract
may  be  made  to  separate  the  indigo ;  the  chloroform  will  rise
to  the  top  of  the  solution,  carrying  with  it  the  indigo.
2.  Tissues  containing  indicane  on  exposure  to  the  vapour
of  alcohol  for  twenty-four  hours  will  turn  blue ;  the  reaction
will  be  better  marked  if  the  chlorophyll  be  subsequently  dis-
solved out  with  absolute  alcohol.
