﻿RELATION 
  OF 
  AQUATIC 
  PLANTS 
  TO 
  SUBSTRATUM. 
  

  

  495 
  

  

  were 
  notched 
  at 
  convenient 
  intervals 
  and 
  upon 
  these 
  the 
  plants 
  were 
  mounted 
  in 
  the 
  

   following 
  manner: 
  One 
  fa(« 
  of 
  the 
  wooden 
  bar 
  was 
  covered 
  with 
  a 
  ribbon 
  of 
  cheese 
  

   cloth, 
  fastened 
  with 
  bits 
  of 
  cotton 
  twine 
  which 
  encircled 
  the 
  bar 
  at 
  the 
  notches. 
  A 
  

   second 
  ribbon 
  of 
  cheese 
  cloth 
  was 
  fastened 
  over 
  the 
  first 
  at 
  one 
  end 
  of 
  the 
  bar. 
  As 
  

   the 
  plants 
  were 
  placed 
  in 
  the 
  intervals 
  between 
  the 
  notches 
  the 
  outer 
  ribbon 
  of 
  

   cheese 
  cloth 
  was 
  passed 
  over 
  them 
  and 
  tied 
  to 
  the 
  bar 
  so 
  as 
  to 
  hold 
  them 
  securely. 
  

   Fifty 
  plants 
  were 
  mounted 
  in 
  this 
  manner, 
  all 
  manipulation 
  being 
  performed 
  under 
  

   water. 
  Of 
  these 
  50 
  individuals 
  25 
  were 
  planted 
  in 
  the 
  box 
  containing 
  soil, 
  so 
  that 
  

   the 
  roots 
  were 
  buried 
  in 
  the 
  mud, 
  the 
  bars 
  being 
  weighted 
  at 
  each 
  end. 
  The 
  remain- 
  

   ing 
  25 
  plants 
  were 
  placed 
  in 
  the 
  box 
  not 
  containing 
  a 
  substratum. 
  The 
  bars 
  on 
  

   which 
  the 
  plants 
  were 
  mounted 
  were 
  set 
  horizontally 
  15 
  cm. 
  above 
  the 
  bottom 
  of 
  

   the 
  box. 
  

  

  The 
  plants 
  were 
  taken 
  from 
  the 
  lake 
  by 
  means 
  of 
  a 
  long-handled 
  shovel, 
  with 
  

   which 
  a 
  portion 
  of 
  soil 
  containing 
  several 
  plants 
  could 
  be 
  raised. 
  By 
  carefully 
  wash- 
  

   ing 
  away 
  the 
  mud, 
  specimens 
  could 
  Ije 
  secured 
  without 
  injury 
  to 
  the 
  roots. 
  Young 
  

   plants 
  of 
  uniform 
  size 
  were 
  selected. 
  

  

  At 
  the 
  end 
  of 
  four 
  weeks 
  in 
  the 
  aquaria 
  the 
  plants 
  were 
  gathered, 
  carefully 
  washed, 
  

   and 
  air-dried. 
  The 
  total 
  weight 
  of 
  suspended 
  plants 
  was 
  15 
  grams 
  and 
  of 
  those 
  

  

  Fjg. 
  l.— 
  Vallisneria 
  sjnralis 
  after 
  7 
  weeks 
  growth 
  rooted 
  in 
  lake 
  soil, 
  i 
  urus 
  1 
  iunl 
  'J. 
  origi- 
  

  

  nally 
  the 
  same 
  size. 
  

  

  rooted 
  in 
  soil 
  20 
  grams, 
  a 
  difference 
  of 
  :-;3i 
  per 
  cent 
  of 
  the 
  former. 
  The 
  plants 
  rooted 
  

   in 
  soil 
  looked 
  as 
  strong 
  and 
  healthy 
  as 
  those 
  in 
  the 
  lake, 
  and 
  several 
  new 
  individuals 
  

   had 
  arisen 
  from 
  the 
  rhizomes. 
  The 
  anchored 
  plants 
  did 
  not 
  look 
  so 
  well; 
  only 
  a 
  

   few 
  new 
  individuals 
  had 
  appeared, 
  and 
  these 
  were 
  stunted 
  in 
  growth. 
  The 
  original 
  

   plants 
  had 
  grown 
  very 
  little. 
  

  

  Experiment 
  No. 
  ^.— 
  This 
  experiment 
  also 
  was 
  conducted 
  at 
  Put-in 
  Bay, 
  Ohio, 
  during 
  

   the 
  period 
  of 
  seven 
  weeks 
  from 
  July 
  18 
  to 
  September 
  5. 
  It 
  will 
  be 
  noticed 
  that 
  in 
  

   the 
  preceding 
  experiment, 
  the 
  roots 
  of 
  the 
  suspended 
  plants 
  were 
  exposed 
  to 
  the 
  

   light 
  prevailing 
  at 
  the 
  depth 
  of 
  60 
  cm. 
  That 
  this 
  condition 
  was 
  not 
  a 
  disturbing 
  

   facttor 
  may 
  be 
  inferred 
  from 
  the 
  following 
  experiment: 
  

  

  Two 
  rectangular 
  glass 
  aquaria, 
  each 
  with 
  a 
  capacity 
  of 
  appi'oximately 
  50 
  liters, 
  were 
  

   located 
  on 
  the 
  lake 
  shore. 
  One 
  contained 
  a 
  layer 
  of 
  lake 
  soil 
  5 
  cm. 
  deep, 
  the 
  other 
  

   carefully 
  washed 
  fine 
  gravel 
  from 
  the 
  lake. 
  The 
  same 
  number 
  of 
  plants, 
  uniform 
  m 
  

   size, 
  was 
  planted 
  in 
  each. 
  The 
  water 
  in 
  the 
  aquaria 
  was 
  siphoned 
  off 
  daily 
  and 
  fresh 
  

   water 
  from 
  the 
  lake 
  supplied. 
  

  

  