﻿RELATION 
  OF 
  AQUATIC 
  PLANTS 
  TO 
  SUBSTRATUM. 
  491 
  

  

  Ludwi^ 
  (1891) 
  gives 
  expression 
  to 
  the 
  current 
  opinion 
  that 
  the 
  roots 
  

   of 
  aquatic 
  plants 
  serve 
  only 
  for 
  attachment 
  and 
  are 
  without 
  root 
  

   hairs, 
  and 
  refers 
  to 
  Schenck. 
  

  

  Wieler 
  (1893) 
  states 
  that 
  Elodea 
  and 
  Ceratophyllum 
  bleed, 
  and 
  since 
  

   the 
  vascular 
  system 
  of 
  these 
  plants 
  is 
  very 
  rudimentary 
  the 
  move- 
  

   ment 
  of 
  water 
  must 
  occur 
  in 
  the 
  intercellular 
  spaces, 
  into 
  which 
  water 
  

   is 
  forced 
  by 
  adjacent 
  cells, 
  perhaps 
  as 
  in 
  land 
  plants. 
  In 
  consideration 
  

   of 
  this 
  opinion 
  it 
  is 
  only 
  necessary 
  to 
  note 
  that 
  mere 
  bleeding 
  does 
  not 
  

   necessarily 
  signify 
  an 
  ascending 
  current, 
  similar 
  to 
  that 
  of 
  land 
  plants. 
  

  

  In 
  the 
  Bonn 
  text-book 
  (Noll, 
  1903) 
  is 
  the 
  assertion 
  that 
  in 
  general 
  

   it 
  is 
  true 
  of 
  all 
  submerged 
  aquatics, 
  even 
  phanerogams, 
  that 
  thej^ 
  are 
  

   able 
  to 
  absorb 
  nutritive 
  solutions 
  thi'ough 
  the 
  surface 
  of 
  the 
  whole 
  

   body, 
  and 
  plants 
  obtaining 
  their 
  food 
  in 
  this 
  way 
  either 
  have 
  no 
  roots 
  

   or 
  the 
  roots 
  serve 
  merely 
  as 
  mechanical 
  holdfasts. 
  

  

  Hochreutiner 
  (1896) 
  was 
  the 
  last 
  to 
  investigate 
  the 
  transport 
  of 
  water 
  

   in 
  submerged 
  plants. 
  His 
  experiment 
  No. 
  1 
  , 
  with 
  Ranunculus 
  aquatilis^ 
  

   illustrates 
  the 
  method 
  employed 
  by 
  him. 
  Two 
  vessels 
  standing 
  adja- 
  

   cent 
  were 
  used, 
  one 
  containing 
  aqueous 
  eosin 
  solution 
  and 
  the 
  other 
  

   "pure" 
  water. 
  One 
  cutting 
  had 
  its 
  base 
  immersed 
  in 
  the 
  eosin 
  to 
  a 
  

   depth 
  of 
  1.5 
  cm. 
  and 
  its 
  upper 
  portion 
  immersed 
  in 
  "pure" 
  water. 
  A 
  

   second 
  cutting 
  had 
  9 
  cm. 
  of 
  its 
  upper 
  part 
  in 
  eosin 
  and 
  its 
  base 
  in 
  

   "pure" 
  water. 
  The 
  exposed 
  parts 
  were 
  greased 
  to 
  prevent 
  capillarity 
  

   and 
  the 
  preparation 
  was 
  kept 
  in 
  a 
  saturated 
  atmosphere. 
  After 
  a 
  day 
  

   and 
  a 
  half 
  it 
  was 
  found 
  that 
  the 
  eosin 
  could 
  be 
  detected 
  in 
  the 
  main 
  

   stem 
  of 
  the 
  first 
  plant 
  9.6 
  cm. 
  from 
  its 
  base; 
  in 
  a 
  lateral 
  branch 
  6 
  cm.; 
  

   in 
  a 
  leaf 
  8 
  cm. 
  The 
  second 
  plant, 
  having 
  9 
  cm. 
  of 
  its 
  upper 
  stem 
  in 
  

   the 
  eosin, 
  showed 
  a 
  coloration 
  in 
  the 
  vascular 
  system 
  through 
  only 
  the 
  

   apical 
  3 
  cm. 
  of 
  the 
  stem. 
  Hochreutiner 
  concludes 
  that 
  in 
  these 
  plants 
  

   there 
  is 
  an 
  upward 
  current; 
  and 
  although 
  there 
  may 
  be 
  some 
  absorption 
  

   by 
  the 
  leaves, 
  it 
  is 
  slight 
  compared 
  with 
  that 
  of 
  the 
  roots, 
  these 
  aquatics 
  

   obtaining 
  their 
  nourishment 
  in 
  the 
  same 
  way 
  that 
  land 
  plants 
  do. 
  He 
  

   further 
  argues 
  that 
  since 
  there 
  is 
  an 
  upward 
  current 
  there 
  must 
  be 
  also 
  

   excretion 
  of 
  water 
  by 
  the 
  leaves; 
  and 
  he 
  seems 
  to 
  consider 
  transpira- 
  

   tion, 
  or 
  better, 
  exudation, 
  possible 
  in 
  these 
  cases. 
  He 
  endeavored 
  to 
  

   measure 
  the 
  exudation, 
  but 
  was 
  unable 
  to 
  overcome 
  the 
  practical 
  diffi- 
  

   culties. 
  The 
  one 
  objection 
  to 
  Hochreutiner's 
  experiments 
  is 
  that 
  his 
  

   plants 
  did 
  not 
  have 
  roots", 
  and 
  that 
  the 
  eosin 
  entered 
  the 
  exposed 
  vas- 
  

   cular 
  system. 
  Although 
  he 
  showed 
  that 
  capillarity 
  would 
  not 
  account 
  

   for 
  the 
  rate 
  of 
  current, 
  it 
  still 
  remains 
  that 
  conclusions 
  as 
  to 
  the 
  behav- 
  

   ior 
  of 
  plants 
  with 
  roots 
  can 
  not 
  Ije 
  drawn 
  from 
  the 
  behavior 
  of 
  plants 
  

   without 
  roots. 
  

  

  « 
  Hochreutiner 
  ( 
  1896). 
  In 
  a 
  review 
  of 
  this 
  article, 
  in 
  Botanisches 
  Centralblatt, 
  1898, 
  

   vol. 
  68, 
  p. 
  366, 
  it 
  is 
  stated 
  that 
  the 
  eosin 
  was 
  offered 
  to 
  the 
  roots, 
  but 
  reference 
  to 
  the 
  

   original 
  shows 
  this 
  is 
  plainly 
  an 
  error. 
  Thus 
  it 
  is 
  probable 
  that 
  A. 
  J. 
  Pieters, 
  Plants 
  

   of 
  Western 
  Lake 
  Erie 
  (Bulletin 
  LI. 
  S. 
  Fish 
  Commission, 
  1901, 
  p. 
  73), 
  had 
  access 
  only 
  

   to 
  the 
  abstract 
  mentioned. 
  

  

  