﻿218 
  Bergman: 
  Internal 
  stomata 
  in 
  ericaceous 
  fruits 
  

  

  Oxycoccus, 
  Maianthemumj 
  Taraxacum, 
  TrifoUtim 
  hybridum 
  and 
  

   Plantago 
  major 
  showed 
  the 
  stomata 
  to 
  be 
  closed. 
  It 
  was 
  found 
  

   that 
  the 
  internal 
  stomata 
  in 
  cranberries 
  were 
  open 
  as 
  fully 
  when 
  

   collected 
  on 
  cloudy 
  days 
  as 
  when 
  collected 
  on 
  clear 
  days. 
  Exam- 
  

   inations 
  of 
  the 
  stomata 
  in 
  the 
  endocarp 
  of 
  cranberries 
  were 
  also 
  

   made 
  from 
  material 
  collected 
  in 
  the 
  evening 
  shortly 
  after 
  sundow 
  n. 
  

  

  r 
  

  

  The 
  stomata 
  were 
  open 
  in 
  this 
  case 
  also. 
  Stomata 
  of 
  other 
  

   plants, 
  at 
  sundown 
  were 
  found 
  to 
  be 
  nearly, 
  if 
  not 
  completely, 
  

   closed. 
  Moreover, 
  an 
  occasional 
  stoma 
  in 
  the 
  cranberry 
  may 
  be 
  

   closed, 
  even 
  when 
  most 
  of 
  them 
  are 
  wide 
  open. 
  Apparently 
  

   these 
  statements 
  apply 
  also 
  to 
  the 
  blueberry 
  and 
  Monotropa 
  

   uniflora^ 
  for 
  in 
  the 
  many 
  examinations 
  of 
  internal 
  stomata 
  from 
  

   these 
  plants 
  which 
  have 
  been 
  made, 
  the 
  stomata 
  have 
  been 
  found 
  

   to 
  be 
  open 
  in 
  nearly 
  all 
  cases. 
  Accordingly, 
  it 
  appears 
  that 
  the 
  

   stomata 
  remain 
  mostly 
  in 
  an 
  open 
  condition 
  and 
  are 
  not 
  functional. 
  

  

  As 
  the 
  internal 
  stomata 
  in 
  the 
  specimens 
  examined 
  apparently 
  

   no 
  longer 
  retain 
  their 
  ability 
  to 
  function, 
  it 
  remains 
  only 
  to 
  account 
  

   for 
  their 
  presence. 
  Morphologically 
  a 
  fruit 
  must 
  be 
  considered 
  

   as 
  a 
  modified 
  leaf 
  or 
  as 
  two 
  or 
  more 
  modified 
  coalesced 
  leaves 
  with 
  

   or 
  without 
  some 
  accessory 
  parts. 
  From 
  the 
  natural 
  position 
  of 
  

   leaves 
  on 
  the 
  plant, 
  it 
  is 
  to 
  be 
  expected 
  that 
  the 
  upper 
  side 
  of 
  the 
  

   leaf 
  would 
  become 
  the 
  inner 
  part 
  or 
  endocarp 
  of 
  the 
  fruit. 
  

  

  It 
  is 
  to 
  be 
  noted, 
  how^ever, 
  that 
  in 
  cranberries 
  and 
  most 
  other 
  

   ericaceous 
  plants 
  the 
  stomata 
  occur 
  only 
  on 
  the 
  under 
  side 
  of 
  the 
  

   foliage 
  leaves. 
  We 
  have 
  then 
  the 
  apparent 
  anomaly 
  of 
  a 
  twisting 
  

   or 
  reversal 
  of 
  position 
  in 
  the 
  fruit. 
  A 
  comparison 
  of 
  the 
  epidermal 
  

   structure 
  of 
  the 
  fruit 
  with 
  that 
  of 
  the 
  upper 
  leaf 
  surface 
  shows 
  

   many 
  similarities. 
  The 
  shape 
  and 
  character 
  of 
  the 
  cells 
  in 
  surface 
  

   view 
  and 
  in 
  cross 
  section 
  show 
  a 
  heavy 
  cuticularized 
  outer 
  wall. 
  

   Similarly 
  the 
  lower 
  epidermal 
  cells 
  of 
  the 
  leaf 
  show 
  a 
  correspon- 
  

   dence 
  with 
  the 
  cells 
  of 
  the 
  endocarp. 
  As 
  far 
  as 
  the 
  similarity 
  of 
  

   the 
  epidermis 
  of 
  the 
  fruit 
  to 
  the 
  upper 
  leaf 
  epidermis 
  is 
  concerned, 
  

   it 
  is 
  without 
  much 
  doubt 
  simply 
  an 
  analogy. 
  The 
  lower 
  side 
  of 
  

   the 
  leaf 
  in 
  becoming 
  modified 
  and 
  transformed 
  into 
  the 
  fruit 
  would 
  

   of 
  course 
  form 
  the 
  outside 
  layer 
  of 
  the 
  fruit. 
  The 
  epidermis 
  of 
  the 
  

   fruit 
  and 
  upper 
  leaf 
  epidermis 
  are 
  both 
  exposed 
  to 
  the 
  same 
  con- 
  

   ditions 
  and 
  both 
  must 
  protect 
  the 
  plant 
  from 
  undue 
  loss 
  of 
  water. 
  

   Accordingly 
  it 
  is 
  not 
  surprising 
  that 
  a 
  similarity 
  in 
  structure 
  has 
  

   resulted 
  in 
  response 
  to 
  identical 
  factors 
  of 
  the 
  environment. 
  

  

  