366  Histology  of  Hyoscyamus  Mutkus.      {AmiuS, Xrm 
CALYX. 
Because  of  the  firm  texture  of  the  calyces,  they  are  less  broken 
than  the  other  parts  of  the  plant.  They  are  10  to  25  mm.  long, 
and  are  borne  on  peduncles  4  to  10  mm.  in  length.  They  are 
gamosepalous,  bell-shaped,  strongly  ribbed,  and  surmounted  by  five 
nearly  equal,  -  short,  blunt  teeth.  In  surface  view  the  epidermis 
resembles  very  closely  that  of  the  leaves  {Fig.  4.  H,  and  M).  Stomata 
occur  on  both  the  inner  and  outer  surfaces  of  the  calyces,  and  both 
surfaces  are  hairy,  although  the  outer  surfaces  soon  become  almost 
smooth.  The  inner  as  well  as  the  outer  epidermis  of  the  calyx  is 
accompanied  by  a  hypodermal  layer  of  cells  similar  in  size  and  form 
to  those  of  the  epidermis  ;  while  between  these  two  zones  of  regular 
cells  lies  a  tissue  of  large  and  very  thin-walled  cells.  In  this  zone 
of  large  cells,  which  is  four  or  five  cells  in  width,  are  many  crystals 
of  calcium  oxalate.    In  color  the  calyx  is  a  greenish-yellow. 
FRUIT. 
The  calyx  closely  surrounds  the  fruit,  but  is  not  attached  to  it. 
The  fruit  is  a  two-locular  pixis,  and  contains  many  small,  light 
brown  or  yellowish  seeds,  which  are  attached  to  the  central  placentae. 
The  seeds,  about  1  mm.  in  diameter,  are  flattened,  nearly  reniform, 
and  finely  reticulate.  The  seed  consists  of  two  very  distinct  coats 
surrounding  a  copious  layer  of  endosperm,  within  which  lies  curled 
up  a  small  colorless  embryo.  The  outer  seed  coat  is  composed  of 
a  single  layer  of  cells  which  have  their  radial  and  inner  tangential 
walls  striated  and  very  much  thickened,  while  the  other  tangential 
wall  remains  thin.  This  thin  outer  wall  usually  collapses  and  lies 
pressed  close  against  the  inner  wall,  thus  giving  the  finely  reticu- 
late structure  to  the  surface  of  the  seed  (Fig.  5,  C).  The  inner  seed 
coat  is  composed  of  a  brownish,  almost  obliterated  or  partly 
resorbed,  zone  of  cells. 
The  endosperm  is  made  up  of  a  zone  of  tissue,  five  or  six  cells 
in  width.  The  cells  are  regular  in  outline,  thin- walled  (Fig.  5, 
A),  and  are  closely  packed  with  aleurone  and  oil.  The  aleurone 
grains  (Fig.  5,  w)  are  four  to  six-sided,  and  four  to  ten  microns  in 
diameter.  Lying  within  the  endosperm  is  the  embryo,  consisting 
of  a  hypocotyl,  and  two  thin-cotyledons  (Fig.  5,  L).  Both  hypocotyl 
and  cotyledons  are  made  up  of  thin-walled  cells  very  similar  in  size 
