378  A  New  Vegetable  Adulterant.        { ^""Xu^^t"  FJil""' 
ish- brown  in  color,  and  more  or  less  fibrous,  due  to  the  shrink- 
ling  of  the  parenchyma  from  the  librovascular  bundles. 
The  taste  of  the  hull  is  markedly  acid  and  somewhat  bitterish, 
but  the  odor  is  not  very  pronounced  or  characteristic. 
Microscopic  Characters. — The  epicarp  shows  the  presence  of 
numerous  broadly  elliptical  stomata  (Fig.  A)  which  are  from  50 
to  70  microns  in  length;  the  opening  between  the  guard-cells  is 
large,  and  sometimes  irregular  in  outline,  or  the  guard  cells  may  be 
separated  along  the  adjoining  walls,  due  to  the  unequal  development 
of  the  tissues.  The  blackish-brown  spots,  which  mark  the  outer 
surface  of  the  epicarp  are  made  up  of  tannin-containing  cells 
which  appear  to  be  under  the  influence  of  a  local  stimulus  of  some 
kind,  the  area  affected  being  0.2  or  0.3  mm.  in  diameter.  The 
epidermal  cells  are  more  or  less  polygonal,  the  cuticle  being  from 
2  to  5  microns  thick  (Fig.  B,  e).  Beneath  the  epidermis  are  two  to 
three  rows  of  tabular  cells,  usually  containing  a  reddish-brown  or 
tannin-containing  sap  (Fig.  B,  c)  ;  beneath  these  sub-epidermal 
cells  is  a  continuous  ring  or  zone  (Fig.  B,  s)  made  up  of  three 
or  four  layers  of  stone  cells,  the  walls  of  which  are  strongly  ligni- 
fied,  lamellated,  and  finely  porous.  The  cells  vary  from  tabular  to 
irregular,  and  may  or  may  not  contain  a  reddish-brown  tannin- 
like substance,  the  tannin  being  in  the  cells  of  the  specialized 
areas  already  described. 
Beneath  this  zone  of  stone  cells  occur  the  tissues  of  the  sarco- 
carp  proper  (Fig.  B,  p).  This  portion  consists  of  parenchyma  and 
fibro-vascular  tissue.  The  cells  of  the  parenchyma  contain  small 
starch  grains  and  occasionally  rosette  aggregates  of  calcium  oxalate 
which  vary  in  diameter  from  25  to  40  microns,  and  sometimes  may 
be  found  in  large  numbers  in  the  parenchyma  cells  adjoining  the 
fibrovascular  bundles. 
The  parenchyma  cells  of  the  sarcocarp  of  the  young  fruits  have 
very  thin  walls,  but  in  the  older  fruits  the  walls  of  very  many 
of  the  cells  become  lignified  and  have  large  oblique  pores.  The 
tracheae  are  in  radial  row^s  two  cells  wide  separated  by  medullary 
rays  one  cell  wide.    They  are  usually  spiral. 
At  both  the  apical  and  basal  portions  of  the  fruit  occur  curved, 
spear-shaped,  unicellular,  non-glandular  hairs  (Fig.  D)  re- 
sembling those  found  in  the  pericarp  of  the  cereal  grains, 
but  distinguished  from  the  latter  by  the  fact  that  they 
are    frequently    united    to    form    stellate    groups  resembling 
