Am'Feb.?i^arm-}  Perfumes  in  Flowers.  93 
the  upper  surface  which  was  hidden  in  the  bud  these  agencies  were 
inoperative,  and  the  same  compounds  were  converted  into  essential 
oil,  which  oxidizes  in  contact  with  the  air  and  produces  the  sensa- 
tion of  perfume. 
Roses. — The  essence  in  roses  is  found  in  the  papilliform  epidermal 
cells1  on  the  upper  surface  of  the  petals,  scarcely  ever  on  the  lov/er 
side.  The  origin  of  the  essence  is  easily  recognized  as  being  the 
same  as  in  the  preceding  case.  The  delicacy  and  the  special  odor  of 
the  essence  furnished  by  each  variety  of  roses  seems  to  depend 
upon  the  more  or  less  complete  transformation  of  the  intermediate 
tannoid  compounds  derived  from  the  chlorophyll. 
Violets.— The  essence  is  here  similarly  situated.  It  is  necessary, 
however,  before  applying  reagents  to  the  sections  in  this  instance 
to  immerse  them  in  tungstate  of  sodium  solution  for  some  minutes, 
in  order  to  precipitate  the  tannin.  The  essential  oil  then  appears 
bright  red. 
Tuberose. — In  this  case,  the  essential  oil  is  found  upon  the  lower 
surface  of  different  parts  of  the  perianth.  The  intermediate  cells 
contain  a  fixed  oil.  Tannin  is  scarcely  perceptible.  Here,  then,  in 
consequence  of  the  abundance  of  chlorophyll  in  the  first  place, 
of  the  almost  complete  absence  of  tannin,  and  also,  probably,  of  the 
presence  of  fixed  oil  which  has  swept  it  towards  the  periphery,  the 
essential  oil  is  carried  towards  the  lower  surface.  The  intense  odor 
of  the  tuberose  only  commences  to  reveal  itself  when  the  oil  is 
enabled  to  form  itself  into  small  drops  under  the  influence  of 
the  reagent. 
Orange. — The  reagent  discloses  the  presence  of  several  distinct 
essences  in  orange  blossoms.  First  there  is  that  of  the  secretory 
sacs,  which  occur  on  the  lower  surface  of  the  petals  or  sepals. 
This  is  not  essence  of  neroli,  as  is  generally  supposed,  but  an 
essence  analogous  to  that  of  petit-grain.  By  skilfully  eliminating 
these  sacs  in  an  unopened  bud,  the  agreeable  odor  of  the  flower 
when  it  afterwards  expands  is  in  no  degree  injured.  Essential  oil 
is  still  found  in  the  epidermis  on  both  surfaces  of  the  petals,  and 
likewise  upon  the  periphery  of  the  petaloid  filaments  of  the  stamens. 
By  systematically  preventing,  in  various  ways,  the  liberation  of  the 
1  Blondel,  "  Produits  odorants  des  Rosiers  "  ("  These  de  la  Faculty  deMed.," 
1889.) 
