﻿RELATION 
  OF 
  AQUATIC 
  PLANTS 
  TO 
  SUBSTRATUM. 
  

  

  507 
  

  

  (1) 
  Soil 
  and 
  tap 
  water, 
  (2) 
  sand 
  and 
  tap 
  water, 
  (3) 
  tap 
  water 
  without 
  

   substratum, 
  (4) 
  Sachs's 
  solution 
  without 
  substratiuii, 
  and 
  (5) 
  Sachs's 
  

   solution 
  with 
  sand 
  substratum. 
  

  

  ELODEA 
  CANADENSIS. 
  

  

  Experiment 
  No. 
  11. 
  — 
  This 
  experiment 
  wa^ 
  conducted 
  at 
  Ann 
  Arbor 
  during 
  the 
  

   i:)eriod 
  from 
  July 
  10 
  to 
  August 
  10. 
  Ten 
  cuttings 
  10 
  cm. 
  long, 
  anchored 
  with 
  bits 
  of 
  

   glass 
  tubing, 
  were 
  suspended 
  in 
  each 
  of 
  five 
  cylindrical 
  battery 
  jars 
  of 
  about 
  3.25 
  

   liters 
  capacity, 
  containing 
  3 
  liters 
  of 
  solution 
  with 
  substrata, 
  as 
  already 
  mentioned 
  

   and 
  as 
  designated 
  in 
  the 
  table. 
  The 
  jars 
  were 
  covered 
  with 
  netting 
  to 
  keep 
  out 
  

   insects 
  and 
  foreign 
  matter, 
  and, 
  to 
  maintain 
  a 
  sufficiently 
  cool 
  temperature, 
  were 
  

   sunk 
  in 
  the 
  earth 
  out 
  of 
  doors 
  to 
  within 
  about 
  6 
  cm. 
  of 
  the 
  top 
  of 
  the 
  jar. 
  The 
  salts 
  

   in 
  the 
  Sachs's 
  solution 
  were 
  present 
  in 
  the 
  same 
  proportion 
  as 
  in 
  the 
  formula, 
  and 
  the 
  

   solution 
  was 
  renewed 
  weekly 
  to 
  prevent 
  the 
  growth 
  of 
  algse. 
  The 
  tap 
  water 
  was 
  of 
  

   course 
  likewise 
  renewed. 
  

  

  Measurement 
  of 
  growth 
  of 
  Elodea 
  canadensis 
  at 
  the 
  end 
  of 
  one 
  inontlt. 
  Original 
  length 
  of 
  

   each 
  cutting, 
  10 
  on. 
  

  

  Specimen 
  

   number. 
  

  

  1 
  

  

  2 
  

  

  3 
  

  

  4 
  

  

  5 
  

  

  6 
  

  

  7 
  

  

  8 
  

  

  9.' 
  

  

  10 
  

  

  Tptal 
  . 
  . 
  . 
  

  

  Average 
  

  

  It 
  will 
  be 
  noticed 
  from 
  this 
  table 
  that 
  four 
  of 
  the 
  plants 
  in 
  Sachs's 
  

   solution 
  died 
  before 
  the 
  experiment 
  was 
  concluded, 
  and 
  it 
  is 
  certainl}^ 
  

   evident 
  that 
  the 
  normal 
  jurowth 
  of 
  the 
  plants 
  was 
  greatly 
  interfered 
  

   with. 
  Of 
  the 
  live 
  conditions 
  tested, 
  that 
  of 
  soil 
  and 
  tap 
  water 
  is 
  cer- 
  

   tainlj^ 
  the 
  best, 
  while 
  that 
  of 
  Sachs's 
  solution 
  without 
  substratum 
  is 
  

   the 
  least 
  favorable. 
  The 
  remaining 
  three 
  conditions 
  can 
  not 
  be 
  said 
  

   to 
  sho\>^ 
  positive 
  differences. 
  

  

  It 
  is 
  a 
  noteworthy 
  fact 
  that 
  not 
  a 
  single 
  root 
  developed 
  on 
  the 
  cut- 
  

   tings 
  anchored 
  in 
  Sachs's 
  solution. 
  Only 
  a 
  few 
  developed 
  in 
  Sachs's 
  

   solution 
  with 
  sand 
  substratum, 
  while 
  in 
  all 
  the 
  tap-water 
  jars 
  the 
  

   development 
  of 
  roots 
  was 
  al)undant. 
  

  

  