﻿200 
  Stork: 
  Studies 
  in 
  the 
  genus 
  Taraxacum 
  

  

  T, 
  vulgare. 
  Several 
  varieties 
  of 
  our 
  common 
  dandelion 
  found 
  

   growing 
  In 
  southern 
  Indiana 
  were 
  drawn 
  into 
  the 
  study, 
  and 
  

   although 
  the 
  material 
  was 
  selected 
  from 
  different 
  varieties, 
  the 
  

   numerous 
  preparations 
  showed 
  no 
  differences 
  in 
  cytological 
  

   behavior. 
  

  

  A 
  second 
  species, 
  T, 
  erythrospermum 
  Andrz., 
  has 
  extended 
  

   itself 
  westward 
  and 
  finds 
  a 
  fairly 
  general 
  distribution 
  throughout 
  

   the 
  middle 
  western 
  states. 
  The 
  sporogenesis 
  of 
  this 
  species 
  was 
  

  

  r 
  

  

  likewise 
  studied 
  and 
  the 
  details 
  of 
  its 
  niegasporogenesis 
  are 
  given 
  

   under 
  a 
  separate 
  heading 
  in 
  the 
  third 
  part 
  of 
  this 
  paper. 
  

  

  - 
  Meantime, 
  numerous 
  castration 
  experiments 
  after 
  the 
  manner 
  

   first 
  employed 
  by 
  Raunkiaer 
  (7) 
  were 
  appHed 
  to 
  plants 
  of 
  several 
  

   varieties 
  of 
  T. 
  vulgare 
  and 
  of 
  T. 
  erythrospermtim. 
  The 
  object 
  

   here 
  was 
  to 
  determine 
  w^hether 
  all 
  these 
  forms 
  set 
  viable 
  seeds 
  in 
  

   the 
  absence 
  of 
  pollination 
  and 
  whether 
  these 
  show 
  the 
  same 
  

   percentages 
  of 
  viability 
  as 
  seeds 
  normally 
  developed. 
  The 
  latter 
  

   species 
  had 
  not 
  been 
  investigated 
  in 
  this 
  respect 
  up 
  to 
  that 
  time. 
  

   Raunkiaer 
  had 
  included 
  a 
  "J", 
  erythrospermum 
  " 
  in 
  the 
  list 
  of 
  plants 
  

   studied 
  by 
  him, 
  but 
  Dahlstedt 
  (2) 
  says 
  that 
  under 
  this 
  name 
  was 
  

   meant 
  T. 
  laetum 
  Dahlst. 
  Since 
  that 
  time 
  Sears 
  (11) 
  has 
  reported 
  

   similar 
  studies 
  before 
  the 
  Ohio 
  Academy 
  of 
  Science. 
  In 
  the 
  

   experiments 
  the 
  excised 
  part 
  of 
  each 
  head 
  was 
  examined 
  to 
  make 
  

   sure 
  that 
  the 
  anthers 
  were 
  all 
  closed 
  and 
  completely 
  removed 
  

   together 
  with 
  the 
  stigmata. 
  If 
  this 
  was 
  not 
  the 
  case 
  the 
  entire 
  

   head 
  was 
  discarded 
  from 
  the 
  experiment. 
  When 
  a 
  head 
  was 
  chosen 
  

   that 
  was 
  too 
  young, 
  the 
  result 
  was 
  that 
  it 
  dried 
  up 
  from 
  too 
  rapid 
  

   a 
  loss 
  of 
  moisture 
  from 
  the 
  cut 
  surface, 
  especially 
  in 
  drying 
  weather. 
  

   It 
  was 
  therefore 
  necessary 
  to 
  select 
  heads 
  at 
  as 
  late 
  a 
  stage 
  as 
  

   possible 
  but 
  before 
  the 
  opening 
  of 
  the 
  loculi 
  of 
  the 
  anthers. 
  When 
  

   these 
  precautions 
  were 
  taken, 
  the 
  heads 
  in 
  all 
  cases 
  developed 
  

   achenes 
  altogether 
  normal 
  In 
  appearance. 
  Germination 
  tests 
  

  

  made 
  

  

  grew 
  

  

  plant. 
  

  

  germinate 
  immed 
  

  

  they 
  are 
  mature. 
  The 
  results 
  of 
  these 
  tests 
  indicated 
  no 
  difference 
  

   in 
  viability 
  between 
  seeds 
  normally 
  developed 
  and 
  those 
  from 
  

  

  w 
  

  

  castrated 
  heads. 
  

  

  Incidentally 
  it 
  may 
  be 
  said 
  that 
  seed 
  formation 
  in 
  Taraxacum 
  

  

  