^m'Mly]mlavm'}MKroscopzcaf  Characters  of  Spurious  Pareira.  253 
into  the  medullary  rays  that  obtains  in  chondodendron.  Immedi- 
ately surrounding  the  medulla  is  an  almost  continuous  zone  of 
thickened  cells,  the  ^cavities  of  which  are  blackened  by  treatment 
with  iodine.  These  cells  are  more  numerous  at  the  apex  of  each  of 
the  wedge- like  woody  bundles.  The  medullary  rays  are  narrow, 
composed  of  tabular  cells  elongated  in  a  radial  direction,  which 
dividing  at  the  end  and  meeting  a  corresponding  division  from  the 
next  ray  overlap  the  bases  of  the  woody  wedges  in  the  same  man- 
ner as  in  true  Pareira.  The  wedge-shaped  woody  bundles  in  the 
zone  immediately  outside  the  medulla  are  much  shorter  than  in 
chondodendron,  and  the  succeeding  zones  are  arranged  much  more 
uniformly.  They  are  composed  of  thickened  wood-cells  and  are 
perforated  by  numerous  large  vessels,  the  cavities  of  which  are 
frequently  filled  by  secondary  growths.  Outside  the  first  zone  of 
woody  bundles  there  is  a  layer  of  sclerenchyma  composed  of  poly- 
gonal cells  with  numerous  and  well  marked  canaliculi.  This  is 
broken  at  intervals  by  crescent-shaped  patches  of  thickened  prosen- 
chyma  (bast)  which  are  more  conspicuous  than  the  similiar  structures 
in  chondodendron.  The  layer  of  sclerenchyma  has  conical  projec- 
tions opposite  the  medullary  rays,  which  fill  the  spaces  left  by  the 
bifurcation  of  the  latter. 
In  the  stem  of  true  pareira  there  is  a  considerable  amount  of 
parenchyma  outside  this  layer,  composed  of  cells  elongated  in  a 
tangential  direction,  and  this  also  obtains  with  the  cells  in  the  mid- 
dle of  the  large  medullary  rays,  whereas  in  the  spurious  variety  now 
under  investigation  the  woody  bundles  of  each  successive  zone 
begin  almost  close  up  to  the  sclerenchymatous  layer.  This,  1  con- 
sider, may  be  a  distinguishing  mark  of  some  value.  The  remaining 
zones  are  each  surrounded  by  a  continuous  layer  of  sclerenchyma. 
Starch  is  present  to  about  the  same  extent  as  in  the  stem  of  chondo- 
dendron, but  a  decoction  of  either  gives  only  a  rusty-red  color  with 
iodine.  The  cells  of  all  the  parenchymatous  tissue  contain  numer- 
ous small,  apparently  octahedral  crystals,  which  might  be  mistaken 
for  starch  granules  unless  tested  with  iodine.  A  longitudinal  section 
shows  numerous  vessels,  with  thickening  distributed  in  oval  patches, 
gradually  passing  into  reticulated  fibres.  These  vessels  have  numer- 
ous prolongations  from  their  walls  meeting  similar  prolongations 
from  contiguous  vessels.  The  large  vessels  of  the  woody  bundles 
are  pitted  with  numerous  slit-like  markings,  arranged  in  a  spiral 
