﻿496 
  REPOET 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  

  

  At 
  the 
  end 
  of 
  seven 
  weeks 
  a 
  very 
  marked 
  difference 
  could 
  be 
  noticed 
  in 
  the 
  

   amount 
  of 
  growth 
  of 
  the 
  two 
  sets 
  of 
  plants. 
  Those 
  in 
  gravel 
  were 
  short, 
  bleached, 
  

   and 
  almost 
  dead. 
  No 
  new 
  shoots 
  had 
  arisen 
  from 
  the 
  rhizomes. 
  The 
  plants 
  in 
  soil 
  

   were 
  in 
  excellent 
  condition, 
  of 
  good 
  size 
  and 
  color, 
  and 
  9 
  new 
  shoots 
  had 
  arisen 
  from 
  

   the 
  rhizomes. 
  (Compare 
  figures 
  1 
  and 
  2.) 
  It 
  is 
  evident 
  that 
  in 
  both 
  of 
  these 
  

   experimentsthedifferencein 
  theamount 
  of 
  growth 
  must 
  be 
  attributed 
  to 
  the 
  difference 
  

   in 
  the 
  environment 
  of 
  the 
  roots. 
  

  

  RANUNCULUS 
  AQUATILIS 
  TKICHOPHYLLUS. 
  

  

  This 
  species 
  lives 
  wholly 
  submerged 
  in 
  shallow, 
  slowly 
  flowing 
  

   water. 
  The 
  leaves 
  are 
  finely 
  dissected 
  and 
  incapable 
  of 
  supporting 
  

   themselves 
  when 
  the 
  plant 
  is 
  taken 
  from 
  the 
  water. 
  The 
  stem 
  

   branches 
  freely, 
  any 
  branch 
  being 
  able 
  to 
  continue 
  the 
  growth 
  of 
  the 
  

   plant 
  if 
  the 
  main 
  stem 
  be 
  removed. 
  Roots 
  may 
  arise 
  at 
  any 
  exposed 
  

   node 
  except, 
  perhaps, 
  the 
  terminal 
  one. 
  If 
  a 
  fragment, 
  a 
  few 
  inter- 
  

   nodes 
  in 
  length, 
  be 
  detached 
  and 
  left 
  floating 
  roots 
  will 
  arise 
  at 
  the 
  

  

  J 
  /:iK\- 
  

  

  Fig. 
  '2.— 
  I 
  alUbnotabjtirahb 
  attLr7-v\eLk 
  

  

  growth 
  niottd 
  in 
  s:r.i\Ll 
  

   the 
  .same 
  size. 
  

  

  Plants 
  in 
  fignres 
  1 
  and 
  2 
  originally 
  

  

  nod(>s 
  in 
  from 
  six 
  to 
  ten 
  days. 
  These 
  roots 
  grow 
  directly 
  downward, 
  

   and 
  shortly 
  after 
  entering 
  the 
  soil 
  contract, 
  at 
  least 
  the 
  stem 
  frag- 
  

   ment 
  is 
  drawn 
  toward 
  the 
  soil. 
  While 
  the 
  roots 
  are 
  elongating 
  toward 
  

   the 
  substratum 
  the 
  stem 
  does 
  not 
  elongate, 
  but 
  it 
  quickly 
  resumes 
  

   growth 
  in 
  length 
  after 
  the 
  roots 
  have 
  entered 
  the 
  soil. 
  More 
  roots 
  

   then 
  arise 
  from 
  higher 
  nodes, 
  and 
  as 
  those 
  enter 
  the 
  soil 
  the 
  plant 
  is 
  

   drawn 
  farther 
  down 
  until 
  it 
  is 
  firmly 
  anchored. 
  The 
  roots 
  do 
  not 
  

   branch 
  before 
  reaching 
  the 
  soil, 
  but 
  do 
  so 
  very 
  shortl}^ 
  after 
  the 
  sub- 
  

   stratum 
  is 
  penetrated. 
  Numerous 
  lateral 
  roots 
  arise 
  and 
  are 
  formed 
  

   in 
  succession 
  as 
  the 
  main 
  root 
  advances. 
  A 
  plant 
  with 
  such 
  a 
  root 
  

   and 
  young 
  lateral 
  roots 
  was 
  carefully 
  removed 
  from 
  the 
  soil 
  and 
  left 
  

   floating. 
  Neither 
  the 
  main 
  root 
  nor 
  its 
  branches 
  continued 
  to 
  grow, 
  

   but 
  new 
  roots 
  arose 
  from 
  the 
  upper 
  nodes 
  which 
  again 
  anchored 
  the 
  

   plant. 
  

  

  