234 
Structure  of  Epigcea  Repens. 
Am.  Jour.  Pharm. 
May,  1895. 
from  each  other  also,  some  having  long  stamens,  others  short  ones, 
and  still  others  those  of  intermediate  length.  There  is  a  correspond- 
ing difference  also  in  the  length  of  the  styles.  The  history  of  the 
flower,  then,  according  to  Prof.  Wilson,  is  as  follows:  It  was  at  first 
hermaphrodite,  and  the  flowers  of  the  species  all  had  the  same 
form.  It  then  became  dimorphous,  later  on  trimorphous,  and  finally 
the  stamens  in  some  flowers  and  the  pistils  in  others  became  abor- 
tive, as  is  the  case  with  the  species  at  the  present  time.  It  may 
therefore  be  safely  predicted  that  in  the  process  of  evolution  still 
going  on  the  last  vestige  of  stamens  from  the  pistillate  flowers,  and 
of  pistils  from  the  staminate  ones,  will  ultimately  disappear. 
The  insertion  of  the  stamens  is,  as  in  most  other  Ericaceae,  on 
the  receptacle,  and  not  on  the  tube  of  the  corolla,  differing  thus 
from  most  other  gamopetalae,  in  which  they  are  adnate  to  the 
tube  of  the  corolla.  The  filaments  are  bearded  at  the  base  and 
alternate  toward  the  apex.  The  anthers  are  introrse,  versatile, 
2-celled,  and  differ  from  those  of  the  majority  of  the  family  in  the 
fact  that  they  dehisce  longitudinally  rather  than  by  means  of 
apical  pores. 
The  pollen  grains  also  differ  from  those  of  most  other  plants  out- 
side this  natural  order  in  the  fact  that  each  is  composed  of  a  group 
of  four  cells. 
The  pistil  is  5-carpeled,  the  ovary  faintly  iO-lobed  exteriorly, 
5-celled  interiorly,  with  an  axile  placentation  and  very  numerous 
ovules.  The  style  is  erect,  unbranching  and  crowned,  in  the  pistil- 
late flower,  with  a  star-shaped,  5-rayed  stigma.  The  stigmas  of  the 
staminate  flowers  are  also  5-lobed,  but  the  lobes  never  open. 
A  study  of  the  cross-section  of  the  stem  shows  such  a  structure 
as  that  drawn  in  Fig.  2  ;  a  small-celled  epidermis,  a  loosely-arranged 
cortical  parenchyma,  whose  cells  vary  greatly  in  size,  a  zone  of  well- 
developed  bast-fibres  in  the  outer  phloem,  a  narrow  zone  of  wood 
with  a  rather  large  pith  composed  of  parenchyma  cells,  some  oi 
which  are  small  or  moderate  in  size,  others  relatively  very  large. 
A  cross-section  of  a  leaf  near  its  base  shows  the  vascular  area 
constituting  the  midrib  to  possess  an  outer  crescent-shaped  mass  of 
bast-fibres,  the  horns  of  which  are  presented  toward  the  upper  sur- 
face of  the  leaf.  Lining  this  is  a  thinner  crescent  of  soft  bast,  which 
in  turn  includes  a  short,  thick  crescentic  mass  of  xylem  tissues.  The 
latter  shows  a  distinct  radial  arrangement  of  its  elements,  and  these 
