﻿520 
  REPORT 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  

  

  tlie 
  translocation, 
  of 
  carboh3^drates 
  ceases, 
  so 
  that 
  if 
  the 
  assimihition 
  

   of 
  carbon 
  dioxid 
  is 
  possible, 
  the 
  assimilatory 
  products 
  will 
  accumulate 
  

   in 
  the 
  leaves 
  until 
  the 
  inhibitory 
  limit 
  is 
  reached, 
  and 
  this 
  result 
  will 
  

   be 
  produced 
  whether 
  the 
  stoppage 
  of 
  g-rowth 
  is 
  due 
  to 
  a 
  deficiency 
  of 
  

   potassium 
  or 
  phosphorus, 
  or 
  to 
  widel}' 
  different 
  causes." 
  From 
  this 
  

   point 
  of 
  view 
  the 
  accumulation 
  of 
  starch 
  is 
  a 
  consequence 
  and 
  not 
  a 
  

   primary 
  cause 
  of 
  retarded 
  growth. 
  

  

  Proteid 
  synthesis 
  is 
  the 
  other 
  very 
  important 
  metabolic 
  process, 
  and 
  

   the 
  chemical 
  analysis 
  does 
  suggest 
  some 
  interference 
  with 
  this 
  func- 
  

   tion. 
  The 
  diminished 
  quantity 
  of 
  potassium 
  and 
  phosphorus 
  may 
  

   mean 
  that 
  the 
  plants 
  could 
  not 
  assimilate 
  these 
  elements 
  rapidly 
  enough 
  

   to 
  furnish 
  proteids 
  for 
  new 
  tissue. 
  (Pfeffer, 
  1900, 
  p. 
  430.) 
  With 
  pro- 
  

   teid 
  synthesis 
  once 
  retarded 
  pathological 
  conditions 
  would 
  soon 
  arise; 
  

   non-diosmosing 
  substances 
  might 
  be 
  formed 
  which 
  would 
  still 
  further 
  

   interfere 
  with 
  normal 
  metaljolism; 
  the 
  activit}^ 
  of 
  enzymes 
  might 
  be 
  

   inhibited, 
  thus 
  favoring 
  starch 
  accunuilation 
  — 
  in 
  fact, 
  we 
  might 
  make 
  

   several 
  suppositions, 
  all 
  of 
  which 
  would 
  be 
  more 
  or 
  less 
  direct]}^ 
  asso- 
  

   ciated 
  with 
  inhil)ited 
  proteid 
  synthesis. 
  On 
  the 
  other 
  hand, 
  starch 
  

   formation 
  itself 
  requires 
  proteids 
  for 
  the 
  plastids; 
  but 
  it 
  is 
  not 
  known 
  

   what 
  may 
  be 
  the 
  capacity 
  for 
  photosj^nthesis 
  of 
  the 
  plastids 
  already 
  

   present 
  before 
  abnormal 
  conditions 
  arise. 
  

  

  Further, 
  it 
  may 
  be 
  asked: 
  Is 
  a 
  uniform 
  environment 
  unfavorable 
  to 
  

   the 
  plant 
  'i 
  When 
  the 
  roots 
  are 
  in 
  contact 
  with 
  the 
  substratum 
  a 
  pos- 
  

   sibly 
  nmch 
  better 
  opportunity 
  is 
  afforded 
  for 
  exercising 
  a 
  quantitative 
  

   selective 
  power 
  than 
  w^hen 
  the}^ 
  are 
  merely 
  hanging 
  in 
  a 
  solution 
  iden- 
  

   tical 
  with 
  that 
  which 
  surrounds 
  the 
  remainder 
  of 
  the 
  plant. 
  Perhaps 
  

   this 
  diversity 
  of 
  environment 
  means 
  much 
  to 
  the 
  plant 
  by 
  way 
  of 
  

   favoring 
  the 
  excretion 
  of 
  waste 
  products 
  as 
  well 
  as 
  securing 
  larger 
  

   quantities 
  of 
  certain 
  salts. 
  

  

  This 
  leads 
  to 
  the 
  final 
  inquiry: 
  Is 
  the 
  function 
  of 
  absorption 
  local- 
  

   ized? 
  The 
  plants 
  which 
  naturally 
  live 
  independently 
  of 
  a 
  substratum 
  

   have 
  a 
  much 
  simpler 
  structure 
  than 
  those 
  like 
  liantmculi/s 
  or 
  Potamog- 
  

   eton^ 
  and 
  it 
  is 
  quite 
  possible 
  that 
  in 
  the 
  latter 
  cases 
  the 
  functions 
  of 
  

   absorption 
  and 
  excretion 
  are 
  so 
  localized 
  that 
  the 
  plant 
  can 
  not 
  con- 
  

   tinue 
  normal 
  metabolism 
  when 
  bat?hed 
  over 
  its 
  entire 
  surface 
  with 
  one 
  

   nutrient 
  solution, 
  even 
  though 
  the 
  solution 
  contain 
  all 
  the 
  necessary 
  

   ingredients 
  in 
  suitable 
  proportion 
  and 
  chemical 
  combination. 
  Possi- 
  

   bly 
  one 
  benefit 
  of 
  a 
  substratum 
  is 
  to 
  furnish 
  the 
  roots 
  with 
  a 
  solution 
  

   which 
  is 
  not 
  isotonic 
  with 
  that 
  which 
  bathes 
  the 
  leaves, 
  although 
  iso- 
  

   tonic 
  must 
  be 
  considered 
  here 
  as 
  applying 
  to 
  each 
  salt 
  individually, 
  as 
  

   the 
  plants 
  have 
  a 
  varying 
  capacity 
  for 
  absorbing 
  and 
  incorporating 
  

   different 
  salts. 
  

  

  The 
  presence 
  of 
  root 
  hairs 
  ma}^ 
  be 
  regarded 
  almost 
  as 
  prima 
  facie 
  

   evidence 
  that 
  the 
  roots 
  bearing 
  them 
  are 
  organs 
  of 
  absorption. 
  That 
  

   root 
  hairs 
  are 
  absent 
  in 
  some 
  few 
  species 
  is 
  not 
  evidence 
  that 
  the}^ 
  are 
  

  

  