﻿Howe: 
  Monosporangial 
  discs 
  in 
  Ltagora 
  5 
  

  

  date" 
  or 
  tripartite 
  divisions 
  of 
  a 
  tetrasporangium 
  and 
  structures 
  

   of 
  this 
  character 
  may 
  have 
  been 
  responsible 
  for 
  the 
  current 
  

   somewhat 
  vague 
  and 
  uncertain 
  alUisions 
  to 
  the 
  existence 
  of 
  tetra- 
  

   spores 
  in 
  the 
  genus 
  Liagora. 
  Occasionally 
  the 
  arrangement 
  of 
  

   the 
  first 
  segments 
  of 
  the 
  young 
  disc 
  suggests 
  that 
  of 
  the 
  carpels 
  

   of 
  an 
  orange, 
  sometimes 
  in 
  apparent 
  contravention 
  of 
  the 
  usual 
  

   rule 
  that 
  a 
  cell 
  divides 
  in 
  a 
  plane 
  perpendicular 
  to 
  its 
  longest 
  axis. 
  

   When 
  the 
  young 
  disc 
  develops 
  to 
  a 
  manifestly 
  flattened 
  form 
  

   while 
  still 
  in 
  its 
  original 
  orientation 
  to 
  the 
  parent 
  filament, 
  it 
  is 
  

   seen 
  (Figs. 
  3, 
  4, 
  and 
  6) 
  that 
  one 
  of 
  its 
  edges 
  is 
  directed 
  towards 
  

   the 
  filament, 
  while 
  the 
  first 
  root-hairs 
  (Figs. 
  5 
  and 
  22), 
  ventral 
  

   and 
  central 
  as 
  regards 
  the 
  disc, 
  are 
  lateral 
  In 
  respect 
  to 
  the 
  fila- 
  

   ment. 
  

  

  In 
  Liagora 
  farinosa 
  Lamour. 
  and 
  L. 
  pinnata 
  Harv., 
  the 
  genetic 
  

   connection 
  of 
  these 
  discs 
  with 
  the 
  Liagora 
  is 
  even 
  more 
  difficult 
  to 
  

   trace 
  than 
  in 
  L. 
  ceranoides 
  and 
  L, 
  valida, 
  owing, 
  apparently, 
  to 
  

   the 
  fact 
  that 
  the 
  aplanospores 
  are 
  released 
  from 
  the 
  more 
  rigid 
  

   mother-cell 
  walls 
  before 
  germination, 
  so 
  that 
  they 
  do 
  not 
  germinate 
  

   in 
  situ. 
  Hyaline, 
  apparently 
  unicellular 
  hairs, 
  usually 
  several 
  

   times 
  as 
  long 
  as 
  the 
  diameter 
  of 
  the 
  disc, 
  arise 
  from 
  the 
  dorsal 
  

   surface 
  and 
  are 
  probably 
  always 
  normally 
  present 
  in 
  younger 
  

   conditions 
  at 
  least, 
  but 
  owing 
  to 
  their 
  delicacy 
  and 
  to 
  their 
  appar- 
  

   ent 
  readiness 
  to 
  dissolve 
  into 
  mucus, 
  they 
  are 
  not 
  always 
  visible, 
  

   especially 
  in 
  L. 
  ceranoides, 
  and 
  they 
  are 
  not 
  represented 
  in 
  our 
  

   figures 
  (Figs. 
  6 
  and 
  18) 
  of 
  the 
  disc 
  in 
  this 
  species. 
  The 
  mature 
  

   discs 
  are 
  suborbicular 
  and 
  are 
  more 
  or 
  less 
  similar 
  in 
  the 
  four 
  

   species 
  of 
  Liagora 
  in 
  which 
  they 
  have 
  thus 
  far 
  been 
  observed 
  by 
  

   the 
  present 
  writer, 
  yet 
  they 
  show 
  differences 
  corresponding 
  to 
  the 
  

   peculiarities 
  of 
  the 
  species 
  of 
  which 
  they 
  constitute 
  a 
  part. 
  In 
  

   L. 
  ceranoides 
  and 
  L. 
  valida, 
  the 
  discs 
  are 
  softer, 
  more 
  mucous, 
  

   and 
  less 
  compact 
  than 
  in 
  L. 
  farinosa 
  and 
  L. 
  pinnata, 
  in 
  which 
  the 
  

   cells 
  of 
  the 
  disc, 
  like 
  those 
  of 
  the 
  assimilatory 
  filaments 
  of 
  the 
  

   main 
  plant, 
  have 
  firmer, 
  more 
  rigid 
  walls. 
  In 
  L. 
  valida, 
  the 
  discs 
  

   are 
  thickened 
  in 
  the 
  central 
  part 
  and 
  often 
  radiately 
  unistratose 
  

   towards 
  the 
  margins, 
  while 
  in 
  L. 
  ceranoides 
  the 
  discs 
  give 
  the 
  

   impression 
  of 
  consisting 
  of 
  more 
  than 
  one 
  layer 
  of 
  cells 
  throughout. 
  

   Fertile 
  discs 
  are 
  mostly 
  90-230 
  /x 
  broad 
  (not 
  Including 
  the 
  mucous 
  

   envelope), 
  though 
  in 
  L. 
  farinosa, 
  the 
  plants 
  of 
  which 
  are 
  commonly 
  

  

  