﻿490 
  KEPORT 
  OP 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  

  

  Sachs 
  (1887) 
  sa3^s: 
  " 
  In 
  algse, 
  and 
  even 
  in 
  some 
  aquatic 
  phanerogams, 
  

   the 
  roots 
  are 
  chiefly, 
  or 
  it 
  may 
  be 
  exclusively, 
  organs 
  of 
  attachment." 
  

  

  Frank 
  (1890) 
  observes 
  that 
  while 
  some 
  aquatics 
  swim 
  freely, 
  there 
  

   are 
  still 
  those 
  whose 
  roots 
  penetrate 
  the 
  substratum 
  and 
  function 
  as 
  

   do 
  the 
  roots 
  of 
  land 
  plants. 
  

  

  Sauvageau 
  (1891) 
  argues, 
  on 
  page 
  281, 
  that 
  if 
  one 
  of 
  the 
  uses 
  of 
  the 
  

   circulation 
  of 
  water 
  in 
  the 
  planf 
  is 
  to 
  supply 
  nutritive 
  substances, 
  this 
  

   ought 
  to 
  be 
  relatively 
  important 
  in 
  the 
  case 
  of 
  submerged 
  plants, 
  

   because 
  the 
  water 
  in 
  which 
  they 
  live 
  is 
  oftentimes 
  less 
  rich 
  in 
  dissolved 
  

   salts 
  than 
  that 
  which 
  circulates 
  in 
  the 
  soil 
  (no 
  authority 
  cited). 
  Con- 
  

   tinuing, 
  he 
  notes 
  that 
  the 
  roots 
  of 
  certain 
  aquatic 
  plants 
  are 
  well 
  

   developed. 
  Species 
  of 
  Potamogetoii, 
  JVaias, 
  and 
  Zostera 
  have 
  well- 
  

   developed 
  roots, 
  and 
  the 
  root 
  hairs 
  persist 
  longer 
  than 
  the 
  other 
  cells 
  

   of 
  the 
  piliferous 
  layer. 
  Species 
  of 
  Potamogeton 
  have 
  leaves 
  of 
  two 
  

   sorts 
  — 
  uarael}", 
  submerged, 
  without 
  stomata, 
  and 
  exposed, 
  witli 
  stomata. 
  

   On 
  page 
  282 
  Sauvageau 
  states 
  that 
  the 
  total 
  surface 
  of 
  the 
  floating 
  

   leaves 
  is 
  always 
  less 
  than 
  that 
  of 
  the 
  submerged. 
  His 
  hypothesis 
  is 
  

   that 
  the 
  processes 
  of 
  absorption, 
  conduction, 
  and 
  giving 
  ofl' 
  of 
  water 
  

   necessitated 
  h\ 
  the 
  floating 
  leaves 
  are 
  not 
  suddenly 
  initiated 
  at 
  the 
  

   moment 
  the 
  floating 
  leaves 
  reach 
  the 
  surface, 
  but 
  must 
  have 
  been 
  in 
  

   operation 
  during 
  the 
  period 
  when 
  the 
  floating 
  leaves 
  were 
  still 
  undevel- 
  

   oped, 
  and 
  likewise 
  in 
  those 
  plants 
  wholl}^ 
  submerged, 
  since 
  their 
  roots 
  

   serve 
  not 
  only 
  mechanically 
  for 
  attachment, 
  but 
  also 
  for 
  absorption. 
  

   On 
  page 
  285 
  he 
  claims 
  to 
  have 
  demonstrated, 
  by 
  direct 
  measurement 
  of 
  

   the 
  water 
  passing 
  through 
  the 
  stem 
  of 
  immersed 
  cuttings, 
  that 
  aquatic 
  

   plants 
  absorb 
  and 
  give 
  off 
  water 
  by 
  a 
  process 
  comparable 
  to 
  tliat 
  of 
  

   land 
  plants. 
  It 
  must 
  be 
  noted, 
  however, 
  that 
  in 
  his 
  experiments 
  only 
  

   fragments 
  of 
  plants 
  were 
  used. 
  In 
  no 
  case 
  did 
  he 
  employ 
  an 
  entire 
  

   plant 
  with 
  roots. 
  He 
  says 
  that 
  if 
  the 
  plants 
  used 
  had 
  been 
  provided 
  

   with 
  roots 
  the 
  absorption 
  would 
  have 
  been 
  greater. 
  A 
  careful 
  review 
  

   of 
  his 
  paper 
  reveals 
  the 
  fact 
  that 
  his 
  conclusion 
  is 
  not 
  warranted. 
  

   Minden 
  (1899) 
  makes 
  the 
  same 
  objection 
  to 
  Sauvageau's 
  conclusion. 
  

  

  Strasburger 
  (1891) 
  observes 
  that 
  in 
  submerged 
  plants 
  the 
  function 
  

   of 
  the 
  trachete 
  is 
  much 
  diminished; 
  that 
  the 
  salts 
  in 
  the 
  surrounding 
  

   water 
  may 
  be 
  absorbed 
  by 
  the 
  entire 
  surface 
  of 
  the 
  plant; 
  and 
  that, 
  

   since 
  there 
  is 
  no 
  transpiration, 
  there 
  is 
  no 
  ascending 
  current. 
  He 
  

   repeated 
  Unger's 
  experiment, 
  previously 
  described, 
  but 
  failed 
  to 
  get 
  

   positive 
  results. 
  Instead 
  of 
  using 
  the 
  same 
  plants 
  that 
  linger 
  used, 
  

   however, 
  he 
  tried 
  Cerato_phyU'um 
  demersum^ 
  and 
  as 
  this 
  plant 
  does 
  not 
  

   develop 
  roots, 
  his 
  negative 
  result 
  has 
  no 
  significance 
  with 
  regard 
  to 
  

   Unger's 
  experiment. 
  Moreover, 
  the 
  value 
  of 
  his 
  experiment 
  is 
  doubt- 
  

   ful 
  because 
  he 
  speaks 
  of 
  allowing 
  his 
  CeratophyUum 
  plants 
  to 
  take 
  

   root 
  in 
  flowerpots 
  before 
  beginning 
  the 
  test 
  — 
  an 
  impossible 
  thing, 
  

   since 
  the 
  plant 
  does 
  not 
  have 
  roots, 
  a 
  fact 
  which 
  he 
  mentions 
  on 
  the 
  

   preceding 
  page. 
  

  

  