﻿508 
  KEPOET 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  

  

  POTAMOGETON 
  PERFOLIATUS. 
  

  

  Experiment 
  No. 
  12. 
  — 
  The 
  location 
  and 
  conditions 
  remain 
  as 
  in 
  the 
  preceding 
  experi- 
  

   ment. 
  The 
  duration 
  of 
  the 
  experiment 
  was 
  from 
  August 
  17 
  to 
  September 
  15. 
  Ter- 
  

   minal 
  portions, 
  10 
  cm. 
  in 
  length', 
  were 
  selected 
  from 
  fresh 
  river 
  plants, 
  and 
  6 
  cuttings 
  

   used 
  in 
  each 
  case. 
  The 
  following 
  table 
  shows 
  the 
  measurements 
  at 
  the 
  end 
  of 
  

   27 
  days: 
  

  

  Measurement 
  of 
  growth 
  of 
  Potamogeton 
  perfoliatus 
  at 
  the 
  end 
  of 
  27 
  dayit. 
  Onginal 
  length 
  

   of 
  each 
  cutting, 
  10 
  cm. 
  

  

  The 
  measurements 
  show 
  — 
  

  

  (1) 
  That 
  for 
  this 
  plant, 
  also, 
  soil 
  and 
  tap 
  water 
  furnishes 
  the 
  most 
  

   favorable 
  of 
  the 
  live 
  environments 
  tested. 
  In 
  this 
  case 
  the 
  plants 
  

   behaved 
  as 
  under 
  corresponding 
  conditions 
  in 
  the 
  aquarium 
  experi- 
  

   ments 
  and 
  as 
  they 
  do 
  in 
  nature. 
  The 
  original 
  cutting 
  grew 
  very 
  

   little, 
  the 
  increase 
  of 
  growth 
  coming 
  from 
  new 
  rhizomes 
  and 
  secondary 
  

   shoots 
  from 
  them. 
  

  

  (2) 
  That 
  Sachs's 
  solution 
  furnishes 
  the 
  least 
  favorable 
  of 
  the 
  live 
  

   environments 
  tested. 
  

  

  (3) 
  That 
  tap 
  water 
  either 
  with 
  or 
  without 
  sand 
  is 
  inferior 
  to 
  soil 
  

   and 
  tap 
  water, 
  but 
  superior 
  to 
  Sachs's 
  solution. 
  

  

  (4) 
  That 
  in 
  this 
  experiment 
  the 
  differences 
  are 
  decisive, 
  and 
  it 
  is 
  pos- 
  

   sible 
  that 
  another 
  test 
  would 
  show 
  Elodea 
  to 
  behave 
  more 
  nearly 
  like 
  

   Potamogeton 
  . 
  

  

  It 
  was 
  also 
  noted 
  that 
  root 
  development 
  in 
  this 
  species 
  i^ 
  greatly 
  

   inhibited, 
  although 
  not 
  completely 
  suppressed, 
  as 
  in 
  the 
  case 
  of 
  Elodea., 
  

   by 
  Sachs's 
  solution. 
  

  

  RANUNCULUS 
  AQUATILIS 
  TRICHOPHYLLUS. 
  

  

  Experiment 
  No. 
  13. 
  — 
  This 
  experiment 
  was 
  conducted 
  in 
  the 
  greenhouse 
  at 
  Ann 
  

   Arbor 
  during 
  the 
  period 
  from 
  November 
  22 
  to 
  December 
  26. 
  Three 
  conditions 
  

   were 
  established. 
  As 
  the 
  plants 
  seem 
  to 
  do 
  better 
  in 
  Sachs's 
  solution 
  when 
  the 
  

   sodium 
  chloride 
  is 
  absent, 
  this 
  salt 
  was 
  omitted 
  in 
  this 
  experiment. 
  The 
  nutrient 
  

   solution 
  was 
  identical 
  in 
  each 
  condition, 
  but 
  one 
  jar 
  contained 
  a 
  soil 
  substratum, 
  

   another 
  sand, 
  and 
  the 
  third 
  was 
  without 
  substratum. 
  The 
  jars 
  stood 
  in 
  the 
  green- 
  

   house 
  and 
  the 
  solutions 
  were 
  renewed 
  weekly. 
  Six 
  cuttings, 
  10 
  cm. 
  in 
  length, 
  were 
  

   selected 
  from 
  the 
  stock 
  aquarium 
  and 
  planted 
  in 
  each 
  j^ir, 
  those 
  in 
  the-jar 
  without 
  

  

  