﻿T. 
  Holm 
  — 
  Studies 
  in 
  the 
  Cyperacece. 
  

  

  lOT 
  

  

  were 
  located 
  on 
  the 
  upper 
  surface 
  of 
  the 
  leaves, 
  but 
  no 
  punc- 
  

   tures 
  were 
  visible, 
  hence 
  the 
  eggs 
  had 
  simply 
  been 
  deposited 
  

   UDon 
  the 
  surface 
  of 
  the 
  leaves, 
  while 
  these 
  were 
  very 
  young 
  

   and 
  their 
  tissues 
  not 
  quite 
  differentiated. 
  

  

  In 
  comparing 
  the 
  internal 
  structure 
  of 
  a 
  diseased 
  leaf 
  with 
  a 
  

   healthy 
  one, 
  the 
  most 
  notable 
  difference 
  seems 
  to 
  lie 
  in 
  the 
  

   epidermis 
  of 
  both 
  faces. 
  This 
  is 
  affected 
  to 
  such 
  an 
  extent 
  

   that 
  the 
  cells 
  have 
  not 
  only 
  become 
  enlarged, 
  but 
  the 
  outer 
  

   wall 
  of 
  each 
  individual 
  cell 
  forms 
  a 
  very 
  distinct 
  and 
  project- 
  

   ing, 
  conical 
  papilla. 
  In 
  the 
  healthy 
  leaf 
  the 
  cells 
  of 
  epidermis 
  

   are 
  rather 
  small 
  on 
  the 
  lower 
  surface 
  with 
  only 
  a 
  few 
  short 
  

   and 
  wart-like 
  protuberances 
  along 
  the 
  margins 
  of 
  the 
  leaf-blade. 
  

   On 
  the 
  upper 
  surface 
  the 
  epidermis 
  consists 
  of 
  larger 
  cells, 
  

   especially 
  above 
  the 
  mesophyll, 
  and 
  wart-like 
  protuberances 
  

   occur 
  here 
  and 
  there 
  near 
  the 
  ribs 
  and 
  along 
  the 
  margins. 
  

   Bulliform- 
  cells 
  are 
  developed 
  as 
  a 
  large 
  group 
  above 
  the 
  mid- 
  

  

  Transverse 
  sections 
  of 
  diseased 
  and 
  healthy 
  leaves 
  of 
  0. 
  stipata. 
  

  

  Fig. 
  2. 
  Epidermis 
  and 
  outer 
  layer 
  of 
  mesophyll 
  from 
  the 
  upper 
  surface 
  of 
  

   diseased 
  leaf. 
  

  

  Fig. 
  3. 
  Epidermis 
  (Ep.), 
  mesophyll 
  (M.), 
  stereome 
  (St.), 
  colorless 
  parenchyma 
  

   (P). 
  and 
  parenchyma-sheath 
  (P.S.) 
  from 
  upper 
  face 
  of 
  healthy 
  leaf. 
  

  

  Fig. 
  4. 
  Epidermis 
  and 
  outer 
  layer 
  of 
  mesophyll 
  from 
  the 
  lower 
  surface 
  of 
  

   diseased 
  leaf. 
  

  

  Fig. 
  5. 
  Epidermis 
  and 
  mesophrll 
  from 
  the 
  lower 
  surface 
  of 
  healthv 
  leaf. 
  

   x240. 
  

  

  rib 
  in 
  both 
  the 
  healthy 
  and 
  diseased 
  leaves, 
  but 
  in 
  the 
  latter 
  

   these 
  cells 
  are 
  very 
  much 
  larger 
  and 
  more 
  numerous. 
  Cells, 
  

   containing 
  silicious 
  cones, 
  occur 
  as 
  usual 
  outside 
  the 
  hypo- 
  

   dermal 
  stereome 
  in 
  the 
  normal 
  leaves, 
  but 
  are 
  almost 
  wanting 
  

   in 
  those 
  diseased 
  ; 
  the 
  same 
  is 
  the 
  case, 
  also, 
  with 
  the 
  stomata, 
  

   which 
  were 
  noticed 
  only 
  on 
  the 
  lower 
  surface 
  of 
  the 
  green 
  

   apex, 
  the 
  other 
  part 
  of 
  the 
  blade 
  being 
  destitute 
  of 
  chlorophyll, 
  

   as 
  stated 
  above. 
  The 
  mechanical 
  tissue, 
  the 
  stereome, 
  is 
  rather 
  

   thin-walled 
  in 
  the 
  affected 
  leaves, 
  but 
  forms 
  here 
  longer 
  and 
  

  

  