﻿RELATION 
  OF 
  AQUATIC 
  PLANTS 
  TO 
  SUBSTRATUM. 
  513 
  

  

  CHEMICAL 
  ANALYSIS. 
  

  

  Chemical 
  analysis 
  has 
  been 
  emplo3^ed 
  for 
  the 
  purpose 
  of 
  securing, 
  

   if 
  possible, 
  some 
  clew 
  to 
  the 
  reason 
  why 
  certain 
  plants 
  can 
  not 
  make 
  

   normal 
  growth 
  unless 
  rooted 
  in 
  soil. 
  Yallisneria 
  was 
  selected 
  as 
  the 
  

   material 
  for 
  analysis, 
  and 
  two 
  sets 
  of 
  plants 
  were 
  grown 
  in 
  floating 
  

   aquaria 
  (the 
  same 
  as 
  described 
  for 
  experiment 
  No. 
  1), 
  stationed 
  in 
  the 
  

   lake 
  at 
  Put-in 
  Bay. 
  One 
  aquarium 
  contained 
  anchored 
  plants 
  only; 
  

   the 
  other 
  contained 
  plants 
  rooted 
  in 
  a 
  soil 
  substratum, 
  and 
  the 
  plants 
  

   were 
  under 
  these 
  conditions 
  for 
  five 
  weeks 
  during 
  July 
  and 
  August. 
  

   At 
  the 
  close 
  of 
  this 
  period 
  each 
  set 
  of 
  plants 
  was 
  gathered 
  and 
  thor- 
  

   oughly 
  washed 
  in 
  running 
  lake 
  water. 
  All 
  unhealthy 
  individuals 
  were 
  

   discarded. 
  The 
  fresh 
  volume 
  of 
  each 
  set 
  was 
  obtained 
  by 
  immersion 
  

   in 
  water, 
  and 
  came 
  so 
  near 
  being 
  the 
  ratio 
  of 
  2 
  to 
  1 
  that 
  a 
  few 
  of 
  the 
  

   suspended 
  plants 
  were 
  left 
  out 
  to 
  secure 
  the 
  ratio. 
  The 
  fresh 
  volume 
  

   of 
  plants 
  rooted 
  in 
  soil 
  was 
  1,380 
  c. 
  c. 
  and 
  of 
  those 
  suspended 
  690 
  c. 
  c. 
  

   This 
  material 
  was 
  then 
  air 
  dried 
  and 
  sent 
  to 
  the 
  U. 
  S. 
  Department 
  of 
  

   Agriculture 
  for 
  analysis, 
  the 
  results 
  of 
  which 
  are 
  recorded 
  in 
  the 
  

   following 
  table: 
  

  

  Annh/sis 
  of 
  YaUhneria 
  spiralis. 
  

  

  Total 
  weight 
  of 
  material 
  air-dried 
  grams. 
  . 
  52. 
  70 
  37. 
  20 
  

  

  Moisture 
  in 
  material 
  air-dried 
  percent.. 
  9.95 
  11.45 
  

  

  Total 
  dry 
  weight, 
  moisture 
  deducted 
  .grams.. 
  47.46 
  32.94 
  

  

  Ether 
  extract 
  in 
  air-dried 
  material 
  percent.. 
  2.51 
  1.63 
  

  

  Crude 
  fiber 
  do.... 
  16.97 
  15.73 
  

  

  Ash 
  do.... 
  20.34 
  17.45 
  

  

  Starch 
  do. 
  . 
  . 
  . 
  2. 
  89 
  6. 
  75 
  

  

  Protein 
  do 
  ... 
  . 
  16. 
  31 
  13. 
  44 
  

  

  Pentosans 
  and 
  ligno-cellulose, 
  by 
  difference 
  do 
  31. 
  03 
  33. 
  55 
  

  

  Keeping 
  in 
  mind 
  that 
  the 
  fresh 
  volume 
  of 
  the 
  anchored 
  plants 
  was 
  

   just 
  one-half 
  that 
  of 
  the 
  plants 
  rooted 
  in 
  soil, 
  it 
  will 
  l>e 
  noticed 
  that 
  

   this 
  ratio 
  is 
  not 
  sustained 
  in 
  either 
  the 
  air-dry 
  weight 
  or 
  the 
  actual 
  

   dry 
  weight. 
  It 
  follows, 
  then, 
  that, 
  per 
  unit 
  of 
  fresh 
  volume, 
  the 
  plants 
  

   anchored 
  contain 
  a 
  larger 
  proportion 
  of 
  dry 
  matter 
  than 
  those 
  rooted 
  

   in 
  soil. 
  On 
  the 
  other 
  hand, 
  the 
  plants 
  rooted 
  in 
  soil 
  contain 
  a 
  larger 
  

   proportion 
  of 
  all 
  the 
  constituents 
  determined 
  except 
  starch, 
  the 
  anchored 
  

   plants 
  having 
  a 
  ver}^ 
  marked 
  increase 
  in 
  the 
  proportion 
  of 
  this 
  constitu- 
  

   ent. 
  The 
  difference 
  in 
  dry 
  weight, 
  then, 
  is 
  attributable 
  to 
  the 
  larger 
  

   starch 
  content 
  of 
  the 
  suspended 
  plants. 
  

  

  F. 
  C. 
  1903—33 
  

  

  