﻿432 
  T. 
  Holm 
  — 
  Studies 
  in 
  the 
  Cyperacece. 
  

  

  to 
  five 
  colorless 
  cells. 
  Yery 
  characteristic 
  of 
  the 
  mesophyll 
  

   are 
  the 
  numerous 
  and 
  large 
  tannin-reservoirs 
  of 
  long, 
  cylindric 
  

   cells, 
  single 
  or 
  several 
  connected 
  together. 
  These 
  reservoirs 
  

   are 
  especially 
  abundant 
  just 
  inside 
  the 
  epidermis 
  of 
  the 
  upper 
  

   face 
  of 
  the 
  leaf, 
  where 
  we 
  have 
  counted 
  no 
  less 
  than 
  fifty 
  

   reservoirs 
  inside 
  a 
  stratum 
  of 
  about 
  one 
  hundred 
  epidermis- 
  

   cells. 
  They 
  are, 
  also, 
  quite 
  abundant 
  in 
  the 
  inner 
  part 
  of 
  the 
  

   mesophyll, 
  around 
  the 
  lacunes, 
  or 
  bordering 
  on 
  the 
  paren- 
  

   chyma 
  sheath 
  of 
  the 
  mestome-bundles. 
  Concerning 
  the 
  gen- 
  

   eral 
  distribution 
  of 
  the 
  mesophyll 
  in 
  the 
  leaf, 
  it 
  appears, 
  on 
  

   examination 
  of 
  transverse 
  sections, 
  to 
  form 
  isolated 
  groups 
  

   between 
  the 
  larger 
  mestome-bundles, 
  which 
  are 
  supported, 
  on 
  

   both 
  faces, 
  by 
  groups 
  of 
  stereome. 
  

  

  The 
  mestome-bundles 
  are 
  all 
  situated 
  in 
  a 
  single 
  plane 
  in 
  the 
  

   leaf, 
  averaging 
  about 
  twenty-five 
  on 
  each 
  side 
  of 
  the 
  midrib; 
  

   they 
  represent 
  two 
  forms, 
  according 
  to 
  their 
  size. 
  The 
  largest 
  

   are 
  the 
  most 
  numerous 
  and 
  differ 
  from 
  the 
  smaller 
  ones 
  by 
  a 
  

   fuller 
  development 
  of 
  their 
  leptome 
  and 
  hadrome 
  ; 
  otherwise 
  

   the 
  structure 
  is 
  identical 
  for 
  both. 
  There 
  is 
  a 
  parenchyma- 
  

   sheath 
  of 
  thin-walled 
  and 
  usually 
  colorless 
  cells, 
  inside 
  of 
  

   which 
  is 
  a 
  constantly 
  closed 
  mestome-sheath,* 
  the 
  cells 
  of 
  

   which 
  are 
  slightly 
  thickened. 
  This 
  inner 
  sheath, 
  by 
  Schwen- 
  

   dener 
  called 
  the 
  mestome-sheath, 
  was 
  first 
  pointed 
  out 
  by 
  this 
  

   author 
  as 
  characteristic 
  of 
  the 
  Cyperacece, 
  Juncacece 
  and 
  a 
  

   number 
  of 
  Graminece. 
  

  

  The 
  leptome 
  and 
  the 
  hadrome 
  are 
  not 
  separated 
  from 
  each 
  

   other 
  by 
  thick- 
  walled 
  mestome-parenchyma, 
  and 
  both 
  are 
  well 
  

   differentiated 
  in 
  the 
  largest 
  bundles. 
  The 
  hadrome 
  contains 
  

   generally 
  two 
  pitted 
  ducts 
  and 
  a 
  few 
  ring-vessels. 
  A 
  small 
  

   lacune 
  is 
  often 
  to 
  be 
  observed 
  above 
  the 
  ring-vessels. 
  

  

  Stereome 
  is 
  not 
  abundant 
  in 
  the 
  leaf, 
  and 
  forms 
  only 
  small 
  

   groups 
  above 
  and 
  below 
  the 
  larger 
  mestome-bundles, 
  while 
  the 
  

   smaller 
  bundles 
  are 
  merely 
  supported 
  by 
  this 
  tissue 
  on 
  their 
  

   hadrome-side 
  ; 
  it 
  does 
  not 
  occur 
  as 
  isolated 
  groups 
  excepting 
  in 
  

   the 
  margins 
  of 
  the 
  blade. 
  The 
  stereome 
  was, 
  in 
  some 
  instances, 
  

   observed 
  to 
  surround 
  tannin-reservoirs, 
  especially 
  on 
  the 
  supe- 
  

   rior 
  face 
  of 
  the 
  leaf. 
  

  

  Having 
  now 
  examined 
  the 
  structure 
  of 
  the 
  assimilating 
  leaf 
  r 
  

   we 
  might 
  in 
  this 
  connection 
  consider 
  the 
  bracts 
  of 
  the 
  inflor- 
  

   escence. 
  There 
  are, 
  as 
  stated 
  above, 
  really 
  two 
  kinds 
  of 
  bracts 
  

   in 
  the 
  inflorescence 
  of 
  Dulichium, 
  viz., 
  those 
  which 
  support 
  

   the 
  spikes, 
  and 
  those 
  which 
  support 
  the 
  single 
  flowers, 
  but 
  

   although 
  their 
  shape 
  is 
  somewhat 
  different 
  their 
  internal 
  struc- 
  

   ture 
  is 
  exactly 
  the 
  same. 
  These 
  bracts 
  show 
  a 
  very 
  firm 
  struc- 
  

   ture 
  due 
  to 
  the 
  extremely 
  thick-walled 
  epidermis 
  of 
  the 
  dorsal 
  

   face, 
  which 
  is 
  the 
  only 
  tissue 
  that 
  constitutes 
  the 
  broad, 
  hyaline 
  

  

  * 
  Schwenderier 
  S. 
  Die 
  Mestomscheiden 
  der 
  Gramineenblatter, 
  Sirzungsber. 
  k. 
  

   Akad, 
  Berlin, 
  1890. 
  

  

  