﻿T. 
  Holm 
  — 
  Studies 
  in 
  the 
  Oyperacece. 
  435 
  

  

  to 
  the 
  biseriate 
  insertion 
  of 
  the 
  flower-bearing 
  spikes. 
  A 
  

   transverse 
  section 
  of 
  the 
  rhachis 
  shows 
  a 
  change 
  in 
  regard 
  to 
  

   the 
  outline, 
  from 
  almost 
  flattened 
  to 
  semicylindric, 
  while 
  the 
  

   minute 
  structure 
  at 
  the 
  same 
  time 
  shows 
  some 
  points 
  of 
  differ- 
  

   ence. 
  The 
  mestome-bundles 
  have 
  moved 
  farther 
  in 
  towards 
  

   the 
  central, 
  colorless 
  fundamental 
  tissue, 
  and 
  most 
  of 
  them 
  

   have 
  lost 
  their 
  outer 
  support 
  of 
  stereomatic 
  tissue. 
  It 
  is 
  only 
  

   on 
  the 
  concave 
  side 
  of 
  the 
  rhachis 
  that 
  the 
  stereome 
  is 
  well 
  

   developed 
  so 
  as 
  to 
  form 
  supporting 
  layers 
  for 
  the 
  mestome- 
  

   bundles. 
  The 
  mesophyll 
  shows 
  the 
  same 
  structure 
  as 
  in 
  the 
  

   peduncle, 
  and 
  it 
  contains 
  several 
  lacunes 
  of 
  rather 
  irregular 
  

   size 
  and 
  shape. 
  

  

  Very 
  different 
  from 
  the 
  peduncle 
  and 
  the 
  rhachis 
  in 
  regard 
  

   to 
  shape 
  and 
  structure 
  is 
  the 
  rhacheola, 
  the 
  axis 
  of 
  the 
  flower- 
  

   bearing 
  spike. 
  It 
  is 
  broadly 
  winged 
  from 
  the 
  decurrent 
  mar- 
  

   gins 
  of 
  the 
  bracts 
  and 
  shows 
  a 
  very 
  simple 
  anatomical 
  struc- 
  

   ture. 
  The 
  epidermis 
  contains 
  tannin 
  in 
  great 
  abundance, 
  and 
  

   the 
  inner 
  tissue 
  is 
  largely 
  composed 
  of 
  a 
  colorless 
  parenchyma 
  

   in 
  which 
  two 
  or 
  three 
  small 
  mestome-bundles 
  are 
  imbedded. 
  

   These 
  are 
  partly 
  surrounded 
  by 
  a 
  single 
  layer 
  of 
  stereome 
  

   besides 
  by 
  a 
  thick-walled 
  parenchyma-sheath 
  ; 
  the 
  elements 
  of 
  

   the 
  leptome 
  and 
  the 
  hadrome 
  are 
  well 
  differentiated. 
  

  

  Having 
  examined 
  the 
  aerial 
  stem 
  of 
  Dulichium 
  with 
  the 
  

   peduncle, 
  the 
  rhachis 
  and 
  the 
  rhacheola, 
  we 
  will 
  now 
  proceed 
  

   to 
  the 
  stem 
  under-ground, 
  the 
  rhizome. 
  The 
  entire 
  structure 
  

   of 
  the 
  rhizome 
  does 
  not 
  show 
  any 
  considerable 
  strength 
  in 
  

   development, 
  which 
  is 
  evidently 
  due 
  to 
  the 
  fact 
  that 
  the 
  soil 
  

   in 
  which 
  our 
  plant 
  grows 
  is 
  generally 
  very 
  soft 
  and 
  loose, 
  and 
  

   does 
  not 
  make 
  any 
  great 
  resistance 
  necessary. 
  The 
  epidermis 
  

   shows 
  naturally 
  a 
  much 
  more 
  simple 
  structure 
  than 
  we 
  observed 
  

   in 
  the 
  stem 
  above-ground, 
  being 
  deprived 
  of 
  stomata 
  and 
  

   epidermal 
  projections. 
  The 
  cell-content 
  is 
  on 
  the 
  other 
  hand 
  

   not 
  only 
  represented 
  by 
  tannin, 
  but 
  also 
  by 
  large 
  deposits 
  of 
  

   starch. 
  Inside 
  the 
  epidermis 
  is 
  a 
  broad 
  layer 
  of 
  thin-walled 
  

   bark-parenchyma, 
  filled 
  with 
  starch, 
  besides 
  that 
  tannin-reser- 
  

   voirs 
  are 
  to 
  be 
  seen 
  in 
  the 
  outermost 
  layers, 
  close 
  to 
  the 
  epider- 
  

   mis. 
  The 
  bark 
  contains 
  only 
  one, 
  but 
  very 
  large 
  lacune, 
  which 
  

   occupies 
  the 
  greater 
  part 
  of 
  the 
  dorsal, 
  the 
  upper 
  part 
  of 
  the 
  

   creeping 
  rhizome. 
  The 
  innermost 
  stratum 
  of 
  the 
  bark-paren- 
  

   chyma 
  is 
  differentiated 
  into 
  a 
  completely 
  closed 
  endodermis, 
  

   which, 
  from 
  the 
  manner 
  in 
  which 
  the 
  cell-walls 
  are 
  thickened, 
  

   represents 
  a 
  typical 
  U-endodermis. 
  A 
  large, 
  starch-bearing 
  

   fundamental 
  tissue 
  is 
  to 
  be 
  observed 
  inside 
  the 
  endodermis, 
  

   and 
  it 
  is 
  here 
  that 
  the 
  mestome-bundles 
  are 
  situated. 
  

  

  These, 
  the 
  mestome-bundles, 
  are 
  all 
  well-devoloped, 
  but 
  are 
  

   not 
  arranged 
  in 
  any 
  order 
  ; 
  they 
  represent 
  two 
  forms, 
  viz, 
  col- 
  

   lateral 
  and 
  concentric 
  or, 
  in 
  this 
  case, 
  perihadromatic, 
  since 
  

  

  