﻿T. 
  Holm 
  — 
  Studies 
  in 
  the 
  Cyperaceoe. 
  433 
  

  

  margins 
  of 
  the 
  bracts. 
  JN~o 
  stomata 
  are 
  to 
  be 
  observed 
  

   and 
  the 
  epidermis 
  does 
  not 
  show 
  any 
  development 
  of 
  

   the 
  so-called 
  bulliform-cells. 
  Epidermal 
  expansions 
  as 
  thorns 
  

   were 
  only 
  observed 
  along 
  the 
  margin, 
  and 
  some 
  of 
  the 
  epi- 
  

   dermis-cells 
  of 
  the 
  ventral 
  face 
  were 
  found 
  to 
  contain 
  tannin. 
  

   There 
  are 
  usually 
  only 
  live 
  mestome-bundles, 
  which 
  are 
  very 
  

   weakly 
  developed, 
  containing 
  merely 
  leptome 
  and 
  no 
  vessels 
  ; 
  

   the 
  mestome-sheath 
  is 
  well-marked 
  and 
  is 
  composed 
  of 
  thick- 
  

   walled 
  cells. 
  There 
  is 
  only 
  a 
  small 
  quantity 
  of 
  mesophyll 
  in 
  

   the 
  bracts, 
  and 
  this 
  forms 
  isolated 
  groups 
  between 
  the 
  mestome- 
  

   bundles, 
  being 
  composed 
  of 
  a 
  few, 
  two 
  or 
  three, 
  layers 
  of 
  

   closely 
  packed 
  polyedric 
  cells. 
  Only 
  a 
  few 
  tannin-reservoirs 
  

   were 
  observed 
  in 
  the 
  mesophyll. 
  

  

  A 
  much 
  stronger 
  development 
  is 
  shown 
  to 
  be 
  possessed 
  by 
  

   the 
  stereome. 
  This 
  tissue 
  shows, 
  however, 
  the 
  same 
  distribu- 
  

   tion 
  as 
  we 
  have 
  seen 
  in 
  the 
  green 
  leaf, 
  but 
  it 
  attains 
  a 
  more 
  

   considerable 
  size 
  in 
  the 
  bracts, 
  where 
  it, 
  also, 
  occurs 
  in 
  several 
  

   isolated 
  groups, 
  viz., 
  on 
  both 
  sides 
  of 
  the 
  midrib 
  and 
  near 
  the 
  

   margins. 
  

  

  The 
  stem, 
  above-ground, 
  is. 
  as 
  we 
  have 
  shown 
  in 
  the 
  preced- 
  

   ing 
  cylindric, 
  hollow 
  and 
  distinctly 
  jointed. 
  It 
  is 
  perfectly 
  

   smooth, 
  since 
  the 
  epidermis 
  is 
  destitute 
  of 
  any 
  projections. 
  

   The 
  epidermis 
  shows, 
  altogether, 
  a 
  very 
  uniform 
  structure 
  like 
  

   we 
  have 
  seen 
  in 
  the 
  leaf, 
  and 
  we 
  find, 
  also, 
  here 
  the 
  internal 
  

   silicious 
  cones 
  in 
  those 
  cells 
  which 
  cover 
  the 
  stereome. 
  Sto- 
  

   mata 
  are 
  present, 
  but 
  rather 
  scarce, 
  forming 
  merely 
  a 
  single 
  

   row 
  between 
  the 
  ribs 
  on 
  the 
  free 
  part 
  of 
  the 
  internodes. 
  

  

  The 
  green 
  bark, 
  the 
  assimilating 
  part 
  of 
  the 
  stem, 
  does 
  not 
  

   form 
  any 
  closed 
  ring 
  in 
  Didichium. 
  It 
  consists 
  of 
  closely 
  

   packed 
  polyedric 
  or 
  roundish 
  cells, 
  and 
  forms, 
  in 
  transverse 
  

   sections, 
  isolated 
  groups 
  between 
  the 
  outer 
  band 
  of 
  mestome- 
  

   bundles. 
  It 
  contains 
  only 
  a 
  small 
  number 
  of 
  tannin-reservoirs, 
  

   which 
  are 
  generally 
  situated 
  close 
  to 
  the 
  large, 
  round 
  lacunes. 
  

   These 
  lacunes 
  correspond 
  in 
  number 
  and 
  arrangement 
  to 
  the 
  

   mesophyll, 
  which 
  borders 
  immediately 
  on 
  their 
  exterior 
  side. 
  

   Inside 
  the 
  ring 
  of 
  lacunes 
  is 
  a 
  rather 
  heavy 
  layer 
  of 
  colorless 
  

   parenchyma, 
  the 
  cells 
  of 
  which 
  are 
  large 
  and 
  roundish, 
  and 
  in 
  

   which 
  an 
  inner 
  band 
  of 
  mestome-bundles 
  is 
  imbedded. 
  The 
  

   center 
  of 
  the 
  internode 
  is 
  occupied 
  by 
  a 
  wide 
  cavity, 
  origi- 
  

   nated 
  from 
  the 
  breaking 
  down 
  of 
  the 
  central 
  mass 
  of 
  funda- 
  

   mental 
  tissue. 
  The 
  nodes 
  themselves 
  are 
  solid 
  and 
  largely 
  

   built 
  up 
  of 
  very 
  thick-walled, 
  star-shaped 
  cells, 
  which 
  are 
  con- 
  

   spicuously 
  porose. 
  

  

  The 
  mestome-bundles 
  of 
  the 
  stem 
  form, 
  as 
  stated 
  above, 
  

   two 
  concentric 
  bands, 
  those 
  of 
  the 
  inner 
  being 
  the 
  largest. 
  

   They 
  are 
  all 
  collateral, 
  and 
  are 
  surrounded 
  by 
  thin-walled 
  

   parenchyma-sheaths 
  ; 
  the 
  leptome 
  and 
  the 
  hadrome 
  is 
  well 
  

   differentiated 
  and 
  sometimes 
  separated 
  by 
  a 
  layer 
  of 
  thick- 
  

   walled 
  mestome-parenchyma. 
  

  

  