﻿RELATION 
  OF 
  AQUATIC 
  PLANTS 
  TO 
  SUBSTRATUM. 
  

  

  503 
  

  

  length 
  of 
  internode 
  were 
  about 
  the 
  f?ame 
  for 
  all, 
  and 
  all 
  of 
  the 
  plants 
  were 
  of 
  fairly 
  

   good 
  green 
  color. 
  Those 
  rooted 
  in 
  soil 
  were, 
  in 
  comparison, 
  of 
  a 
  more 
  delicate 
  green 
  

   and 
  in 
  first-class 
  condition. 
  The 
  stem 
  was 
  less 
  in 
  diameter 
  and 
  the 
  internodes 
  

   markedly 
  longer. 
  The 
  accompanying 
  table 
  shows 
  the 
  total 
  length 
  at 
  the 
  end 
  of 
  one 
  

   month. 
  As 
  only 
  a 
  few 
  branches 
  and 
  rhizomes 
  developed, 
  these 
  are 
  included 
  in 
  the 
  

   total 
  for 
  each 
  plant. 
  

  

  Growth 
  measurements 
  of 
  Elodea 
  canadensis 
  at 
  the 
  end 
  of 
  31 
  days, 
  

   cutting, 
  10 
  cm. 
  

  

  Original 
  length 
  of 
  eacJi 
  

  

  The 
  table 
  shows: 
  

  

  (1) 
  An 
  approximate 
  equality 
  of 
  the 
  anchored 
  plants 
  with 
  one 
  

   another. 
  

  

  (2) 
  A 
  gTeat 
  difference 
  in 
  favor 
  of 
  the 
  plants 
  rooted 
  in 
  soil. 
  

  

  (3) 
  The 
  plants 
  rooted 
  in 
  sand 
  exceed 
  the 
  anchored 
  plants, 
  but 
  hardly- 
  

   enough 
  to 
  establish 
  a 
  positive 
  difference. 
  

  

  Experiment 
  No. 
  7. 
  — 
  August 
  20 
  to 
  September 
  15. 
  Location 
  and 
  conditions 
  as 
  in 
  

   preceding. 
  This 
  plant 
  being 
  an 
  alga 
  and 
  much 
  simpler 
  than 
  any 
  of 
  the 
  preceding 
  

   species 
  in 
  organization, 
  and 
  having 
  rhizoids 
  instead 
  of 
  roots, 
  it 
  seemed 
  probable 
  that 
  

   it 
  would 
  be 
  found 
  to 
  be 
  independent 
  of 
  a 
  soil 
  substratum 
  for 
  optimum 
  growth. 
  Ter- 
  

   minal 
  cuttings 
  15 
  cm. 
  long 
  were 
  selected 
  as 
  in 
  preceding 
  cases 
  and 
  the 
  same 
  experi- 
  

   ment 
  tried. 
  

  

  Groivth 
  measurements 
  of 
  Chara 
  at 
  the 
  end 
  of 
  S6 
  days. 
  Original 
  length 
  of 
  each 
  cutting 
  15 
  cm. 
  

  

  