﻿EELATION 
  OF 
  AQUATIC 
  PLANTS 
  TO 
  SUBSTRATUM. 
  521 
  

  

  unnecessary 
  structures 
  for 
  water 
  plants 
  in 
  general, 
  for 
  there 
  are 
  ter- 
  

   restrial 
  plants 
  (Schwarz, 
  18S1-1885, 
  p. 
  168) 
  whose 
  roots 
  do 
  not 
  develop 
  

   root 
  hairs. 
  

  

  The 
  necessity 
  for 
  going- 
  further 
  into 
  the 
  chemistry 
  of 
  plant 
  metabo- 
  

   lism 
  is 
  apparent, 
  and 
  we 
  can 
  onlj^ 
  say 
  that 
  when 
  these 
  plants 
  are 
  denied 
  

   a 
  substratum 
  of 
  soil 
  the 
  normal 
  processes 
  of 
  metabolism 
  are 
  altered 
  to 
  

   a 
  fatal 
  degree. 
  

  

  CONCLUSIONS. 
  

  

  1. 
  ValUsne?'ia 
  spiralis, 
  RanHncuIus 
  aquatilis 
  trleJiopJiylJus, 
  JElodea 
  

   canadensis^ 
  Myriophyllum 
  spicatum^ 
  Potamogeton 
  ohtusifoUus, 
  and 
  1\ 
  

   perfoliatus 
  are 
  dependent 
  upon 
  their 
  rooting 
  in 
  the 
  soil 
  for 
  optimum 
  

   growth, 
  and 
  can 
  not 
  survive 
  a 
  single 
  season 
  if 
  denied 
  a 
  substratum 
  of 
  

   soil. 
  

  

  2. 
  The 
  roots 
  of 
  these 
  plants 
  are 
  organs 
  of 
  absorption 
  as 
  well 
  as 
  of 
  

   attachment. 
  

  

  3. 
  There 
  is 
  an 
  upward 
  current 
  in 
  these 
  plants, 
  from 
  roots 
  to 
  stem 
  

   and 
  leaves. 
  

  

  4. 
  When 
  these 
  plants 
  are 
  denied 
  a 
  substratum, 
  ^pathological 
  condi- 
  

   tions 
  arise 
  which 
  are 
  manifested 
  by 
  an 
  accumulation 
  of 
  starch 
  and 
  a 
  

   retarded 
  growth 
  with 
  subsequent 
  death. 
  

  

  5. 
  The 
  retarded 
  growth 
  of 
  plants 
  denied 
  a 
  substratum 
  is 
  not 
  due 
  

   to 
  inhibited 
  photosjmthesis. 
  

  

  6. 
  The 
  plants 
  anchored 
  over 
  a 
  soil 
  substratum 
  do 
  not 
  have 
  a 
  more 
  

   favorable 
  environment 
  than 
  those 
  anchored 
  over 
  a 
  clean 
  washed 
  sand 
  

   substratum. 
  

  

  7. 
  Many 
  of 
  the 
  plants 
  rooting 
  in 
  soil 
  develop 
  root 
  hairs, 
  and 
  the 
  

   presence 
  of 
  these 
  structures 
  is 
  the 
  rule 
  rather 
  than 
  the 
  exception. 
  

  

  8. 
  In 
  the 
  case 
  of 
  Ha.nuncnlus 
  aquatilis 
  tricliopliyllus 
  light 
  inhibits 
  

   the 
  formation 
  of 
  lateral 
  roots. 
  

  

  9. 
  CeratophyUam. 
  and 
  some 
  other 
  floating 
  plants 
  are 
  able 
  to 
  absor)) 
  

   their 
  nutrient 
  salts 
  directly 
  from 
  the 
  surrounding 
  water. 
  

  

  From 
  the 
  results 
  of 
  this 
  investigation 
  the 
  following 
  deductions 
  are 
  

   considered 
  probable: 
  

  

  1. 
  The 
  above 
  conclusions 
  are 
  applicable 
  to 
  all 
  aquatic 
  plants 
  which 
  

   grow 
  rooted 
  in 
  a 
  soil 
  substratum, 
  and 
  especialh^ 
  to 
  those 
  whose 
  roots 
  

   are 
  provided 
  with 
  root 
  hairs. 
  

  

  2. 
  The 
  primary 
  cause 
  of 
  the 
  retarded 
  growth 
  of 
  anchored 
  plants 
  is 
  

   their 
  inability 
  to 
  secure 
  enough 
  phosphorus 
  and 
  potassium, 
  and 
  pos- 
  

   sibly 
  other 
  elements. 
  

  

  3. 
  When 
  proteid 
  synthesis 
  is 
  iidiibited 
  by 
  an 
  insufficiency 
  of 
  phos- 
  

   phorus 
  .and 
  potassium, 
  pathological 
  conditions 
  arise 
  which 
  permit 
  the 
  

   accumulation 
  of 
  starch. 
  

  

  4. 
  These 
  plants 
  are 
  terrestrial 
  forms 
  adapted 
  to 
  an 
  aquatic 
  hal)it 
  

   rather 
  than 
  descendants 
  of 
  plants 
  in 
  which 
  the 
  functions 
  of 
  absorption 
  

   and 
  excretion 
  are 
  not 
  localized. 
  

  

  