Am.  Jour.  Pharm.  ) 
May,  1921.  $ 
Pelargonium-Oil. 
307 
gans  is  a.  hybrid  of  P.  odoratissimum  and  the  perennial  P.  exstipu- 
latum,  and  in  its  appearance  resembles  the  former  species,  but  is 
perennial  like  the  latter.  Sweet  (p.  172)  says  that  it  is  an  old  plant 
of  the  English  greenhouses.  I  have  never  seen  these  plants  in  the 
open  or  in  a  herbarium.  In  Algeria  and  Reunion  the  two  species  are 
certainly  not  cultivated. 
MORPHOLOGICAL  CONSTITUTION  OF  THE  GLANDS. 
The  oil  is  furnished  by  the  glands  of  the  plant.  These  are  found, 
as  in  all  pelargonium  species,  in  the  green  parts,  especially  on  the 
surface  of  the  leaves,  where  they  are  shorter  than  on  the  stem  and 
the  peduncles.  In  most  cases  they  are  from  %5  to  Y18  mm.  long 
and  can  be  seen  with  the  naked  eye.  They  consist  of  from  one  to 
three  small  cylindrical  base-cells  and  a  small  globular  head.  The 
number  of  the  base-cells  is  smaller  in  the  gland  hairs  of  the  leaves 
than  in  those  of  the  stems.  All  gland  hairs  originate  in  epidermicat 
cells  which  multiply  by  cross-division.  The  uppermost  of  the  two 
cells  rounds  itself  and  becomes  a  small  head.  Whenever  the  gland 
hair  possesses  more  than  one  base-cell,  the  latter  is  once  more  di- 
vided into  two.  The  spicate  head  is,  therefore,  older  than  the  next 
lower,  and  the  lowest  is  the  youngest.  The  oil  is  mostly  found  only 
in  the  small  head,  rarely  in  the  neighboring  cell.  When  young,  the 
end-cell  is  colorless ;  later  it  is  colored  by  a  yellowish  substance  and 
finally  becomes  brown.  This  substance  often  forms  a  globular  body, 
which,  according  to  Weiss  (pp.  577-599),  who  obtained  this  result 
in  a  related  species,  lie's  at  the  bottom  of  the  cell  and  is  surrounded  by 
a  clear  liquid.  Of  the  numerous  chemical  reactions  I  might  mention 
that  of  iodine,  which  colors  the  young  small  head  bright  yellow,  the 
older  one  dark  yellow  or  almost  brown.  A  solution  of  potash-lye 
(KOH)  gives  a  yellow  color.  Chloride  of  iron  brings  about  the  re- 
action of  tannin. 
The  researches  of  Behrens  (Ueber  einige  aetherisches  Oel  sece- 
fniercnde  Hautdriisen  in  den  Ber.  d.  deutschen  Bot.  Ges.,  IV,  1886, 
p.  400),  which  this  author  made  in  the  glands  of  P.  zonale,  do  not 
completely  agree  with  those  of  Weiss.  According  to  the  former,  the 
oil  originates  in  the  plasm  of  the  cell,  so  that,  upon  adding  alcohol 
vacuoles  may  be  seen.  In  a  later  state  the  oil  lies'  in  the  form  of  a 
meniscus  between  plasma  and  cell-wall.  Finally,  there  is  found  be- 
tween plasma  and  oil  a  stratum  of  cellulose,  which  changes  into  a 
