92 
Perfumes  in  Flowers. 
/Am  Jour.  Pharm. 
I        Feb.,  1893. 
of  the  matter  in  which  the  perfume  of  flowers  is  produced.  I  have 
applied  to  this  class  of  researches  a  general  method  which  has 
served  in  the  localization  of  fixed  oils.  The  section  being  placed  in 
a  drop  of  pure  glycerin  is  arranged  upon  a  round  cover  glass,  which, 
being  then  inverted,  serves  as  a  cover  to  a  small  chamber  formed 
by  cementing  a  glass  ring  to  an  object  slide.  In  the  interior  of  the 
chamber  is  fixed  another  ring  of  smaller  diameter  and  somewhat  less 
in  height,  thus  forming  with  the  first  an  annular  space  in  which  the 
reagent  may  be  placed.  By  adopting  this  arrangement  the  light 
passing  through  the  central  part  of  the  cell  is  not  modified.  The 
inner  ring  will  further  serve  to  support  a  very  small  cover  glass, 
upon  which  sections  may  be  arranged  which  require  to  be  exposed 
to  the  action  of  the  reagent  for  some  length  of  time,  as  occasionally 
happens  in  the  case  of  the  fixed  oils.  The  reagent  invariably 
employed  is  pure  hydrochloric  acid,  the  hydrated  vapors  from 
which  are  readily  absorbed  by  the  glycerin.  In  this  way,  by  a 
gentle  and  easily  regulated  action,  I  obtain  complete  hydration  of 
sections  in  the  presence  of  an  acid.  When  they  have  been  exposed 
for  a  short  time,  the  essential  oils  appear  as  minute  spherical  drops 
of  a  fine  transparent  golden  yellow.  If  the  action  be  prolonged  the 
•drops  disappear,  being  transformed  into  diffusible  products.  The 
tendency  of  the  globules  is  not  seen  in  the  fixed  oils,  so  that  it  pro- 
vides a  means  of  distinguishing  these  two  classes  of  products. 
Jasmin. — In  this  flower  the  essence  is  situated  in  the  row  of 
epidermal  cells  on  the  upper  side  of  the  petals  and  sepals.  Some 
exist  also  in  the  corresponding  layer  on  the  under  surface,  where 
the  sepals  are  colored  by  a  violet  pigment.  If  the  evolution  of  the 
cell  contents  in  flowers  at  different  stages  of  development  be 
followed,  at  first  nothing  but  chlorophyll  is  found  in  the  tissue ; 
tannin  appears  next,  or  rather  intermediate  glucosides,  difficult 
to  identify  by  means  of  the  ordinary  tests  for  these  substances. 
These  glucosides  furnish  the  tannin  and  pigments  of  the  lower 
surface  of  the  sepals.  The  hydrochloric  acid  vapors  distinguish  all 
the  tannoid  compounds  intermediate  between  the  chlorophyll  and 
tannin  or  pigments  on  the  one  hand,  and  between  the  chlorophyll 
and  essential  oil  on  the  other.  The  explanation  of  these  facts  seem  to 
be  as  follows:  Whereas  upon  the  lower  surface  of  the  bud,  which  was 
exposed  to  the  action  of  light  and  the  oxygen  of  the  air,  the  tan- 
noid compounds  were  slowly  oxidized  and  gave  rise  to  tannin,  upon 
