﻿1890. 
  J 
  BOTANICAL 
  GAZETTE. 
  3 
  

  

  F 
  

  

  tive 
  condition. 
  It 
  would 
  be 
  as 
  reasonable 
  to 
  argue 
  that, 
  be- 
  

   cause 
  in 
  man 
  the 
  hand 
  is 
  pentadactyl, 
  while 
  in 
  the 
  horse 
  it 
  is 
  

   monodactyl, 
  that 
  the 
  latter 
  approaches 
  in 
  this 
  respect 
  more 
  

   nearl}^ 
  the 
  primitive 
  mammalian 
  type 
  than 
  does 
  the 
  former, 
  

   being 
  admittedly 
  an 
  animal 
  of 
  lower 
  rank 
  than 
  man. 
  

  

  The 
  Leptosporangiata^ 
  may 
  therefore 
  be 
  looked 
  upon 
  as 
  

   bearing 
  much 
  the 
  same 
  sort 
  of 
  relation 
  to 
  the 
  eusporangiate 
  

   pteridophytes 
  and 
  spermaphytes 
  as 
  some 
  such 
  peculiarly 
  

  

  specialized 
  group 
  as 
  the 
  ungulates 
  bears 
  to 
  the 
  other 
  mam- 
  

   malia. 
  

  

  If 
  we 
  examine 
  the 
  different 
  groups 
  of 
  the 
  pteridophytes, 
  

   where 
  shall 
  we 
  find 
  the 
  form 
  that 
  corresponds 
  most 
  nearly 
  

   to 
  this 
  assumed 
  primitive 
  type 
  ? 
  I 
  think 
  the 
  answer 
  is 
  Ophi- 
  

   oglossum. 
  In 
  such 
  a 
  form 
  as 
  O. 
  vulgatum 
  the 
  sporophyte 
  is 
  

   reduced 
  to 
  almost 
  its 
  simplest 
  expression, 
  little 
  more 
  than 
  a 
  

   single 
  two-lobed 
  leaf 
  and 
  a 
  few 
  roots 
  of 
  the 
  simplest 
  form, 
  

   the 
  stem 
  being 
  reduced 
  to 
  a 
  minimum. 
  The 
  sporangia 
  are 
  

   mere 
  cavities 
  in 
  the 
  tissue 
  of 
  the 
  fertile 
  leaf-segment, 
  scarcely 
  

   indicated 
  on 
  the 
  surface 
  and 
  covered 
  over 
  with 
  an 
  undiffer- 
  

   entiated 
  stoma-bearing 
  epidermis. 
  If 
  we 
  compare 
  this 
  with 
  

   the 
  sporogonium 
  of 
  Anthoceros 
  we 
  shall 
  find 
  in 
  the 
  latter 
  that 
  

   the 
  greatest 
  difference, 
  aside 
  from 
  the 
  absence 
  of 
  true 
  fibro- 
  

   vascular 
  bundles, 
  is 
  that 
  the 
  sporogenous 
  tissue 
  forms 
  a 
  

   continuous 
  layer 
  surrounding 
  the 
  columella. 
  The 
  epidermis 
  

   develops 
  stomata 
  of 
  precisely 
  the 
  same 
  character 
  as 
  those 
  of 
  

   Ophioglossum^ 
  and 
  other 
  vascular 
  plants. 
  Separate 
  the 
  

   sporogenous 
  tissue 
  in 
  distinct 
  sporangia, 
  each 
  with 
  its 
  own 
  

   external 
  opening, 
  and 
  develop 
  a 
  few 
  vessels 
  in 
  the 
  columella, 
  

   and 
  we 
  have 
  a 
  structure 
  approaching 
  very 
  near 
  to 
  what 
  

   really 
  attains 
  in 
  the 
  fertile 
  segment 
  of 
  the 
  leaf 
  of 
  Ophio- 
  

   glossum. 
  

  

  The 
  tissues 
  of 
  the 
  Ophioglossacese 
  are 
  remarkably 
  simple 
  

   in 
  structure, 
  this 
  being 
  most 
  noticeable 
  in 
  Ophioglossum.-"^ 
  

   In 
  the 
  latter 
  the 
  predominating 
  tissue 
  is 
  an 
  undifferentiated 
  

   spongy 
  parenchyma.^ 
  No 
  special 
  hypoderma 
  is 
  recogniza- 
  

   ble, 
  the 
  absence 
  of 
  the 
  abundant 
  sclerenchyma 
  of 
  most 
  pterid- 
  

   ophytes 
  being 
  very 
  noticeable, 
  as 
  well 
  as 
  the 
  small 
  size 
  and 
  

   simple 
  structure 
  of 
  the 
  fibro-vascular 
  bundles. 
  The 
  stem 
  

   and 
  root 
  grow 
  from 
  a 
  single 
  apical 
  cell, 
  indicating 
  thus, 
  ac- 
  

   cording 
  to 
  Bower's 
  view,'^ 
  a 
  primitive 
  condition 
  as 
  compared 
  

   with 
  the 
  higher 
  pteridophytes 
  and 
  spermaphj-tes. 
  

  

  Unfortunatelv 
  our 
  knowledo-p 
  nf 
  fhf^ 
  nrntV»Qlliiim 
  onrJ 
  or^_ 
  

  

  •Gcebel, 
  **Outlines," 
  p. 
  250 
  

   ^Op. 
  cit. 
  

  

  *L. 
  c. 
  p. 
  318. 
  366. 
  

  

  