﻿RELATION 
  OF 
  AQUATIC 
  PLANTS 
  TO 
  SUBSTEATUM. 
  511 
  

  

  The 
  base 
  of 
  the 
  cutting, 
  including 
  the 
  adjacent 
  portion 
  of 
  the 
  root, 
  being 
  wrapped 
  

   in 
  the 
  stopper, 
  the 
  plant 
  was 
  located 
  with 
  the 
  longer 
  root 
  inside 
  a 
  narrow-mouth 
  

   bottle 
  partly 
  filled 
  with 
  lithium 
  nitrate 
  solution. 
  The 
  preparation 
  was 
  then 
  sub- 
  

   merged 
  in 
  an 
  aquarium, 
  this 
  arrangement 
  leaving 
  the 
  shorter 
  root 
  outside 
  the 
  bottle 
  

   and 
  serving 
  as 
  a 
  check 
  on 
  diffusion 
  from 
  tlie 
  bottle. 
  The 
  distance 
  from 
  the 
  base 
  of 
  

   the 
  cutting 
  to 
  the 
  level 
  of 
  the 
  solution 
  in 
  the 
  bottle 
  being 
  4 
  cm., 
  any 
  lithium 
  escap- 
  

   i 
  ng 
  from 
  the 
  bottle 
  except 
  through 
  the 
  tissues 
  of 
  the 
  plant 
  would 
  have 
  to 
  do 
  so 
  by 
  

   capillarity 
  along 
  this 
  root. 
  The 
  preparation 
  was 
  left 
  standing 
  twenty-four 
  hours. 
  

   The 
  temperature 
  was 
  17° 
  C. 
  and 
  the 
  weather 
  cloudy. 
  

  

  Upon 
  examination 
  lithium 
  was 
  found 
  in 
  all 
  parts 
  of 
  the 
  stem 
  and 
  leaves, 
  except 
  

   the 
  terminal 
  node 
  and 
  leaf. 
  No 
  lithium 
  could 
  be 
  detected 
  in 
  the 
  root 
  outside 
  the 
  

   bottle, 
  not 
  even 
  within 
  2 
  millimeters 
  of 
  its 
  union 
  with 
  the 
  stem. 
  

  

  Experiment 
  No. 
  i5.— 
  This 
  experiment 
  was 
  also 
  performed 
  in 
  the 
  greenhouse, 
  the 
  

   date 
  being 
  March 
  2. 
  In 
  this 
  case 
  conditions 
  were 
  the 
  same 
  as 
  in 
  the 
  preceding 
  

   experiment, 
  except 
  that 
  the 
  cutting 
  was 
  allowed 
  to 
  root 
  in 
  a 
  sand 
  substratum 
  and 
  

   develop 
  numerous 
  lateral 
  roots. 
  This 
  furnished 
  a 
  normal 
  root 
  system, 
  and 
  thus 
  bet- 
  

   ter 
  material 
  for 
  securing 
  an 
  indication 
  of 
  the 
  probable 
  rate 
  of 
  current 
  in 
  the 
  plant. 
  

   After 
  the 
  plant 
  was 
  well 
  rooted 
  the 
  sand 
  was 
  carefully 
  washed 
  away 
  with 
  as 
  little 
  

   injury 
  to 
  the 
  roots 
  as 
  possible. 
  The 
  cutting 
  was 
  then 
  left 
  suspended 
  for 
  three 
  weeks 
  

   to 
  allow 
  any 
  injuries 
  to 
  the 
  roots 
  to 
  heal. 
  The 
  stem 
  of 
  the 
  cutting 
  from 
  base 
  to 
  tip 
  

   measured 
  40 
  cm. 
  Two 
  roots, 
  well 
  branched, 
  descended 
  from 
  the 
  basal 
  node. 
  Both 
  

   of 
  these 
  roots 
  were 
  placed 
  in 
  the 
  bottle. 
  Other 
  roots 
  arising 
  from 
  higher 
  nodes 
  were 
  

   left 
  outside 
  the 
  bottle. 
  The 
  distance 
  from 
  the 
  base 
  of 
  the 
  stem 
  to 
  the 
  level 
  of 
  the 
  

   lithium 
  nitrate 
  solution 
  was 
  4 
  cm. 
  The 
  duration 
  of 
  the 
  test 
  was 
  11.30 
  a. 
  m. 
  to 
  4.30 
  

   p. 
  m., 
  the 
  temperature 
  20° 
  C, 
  the 
  sky 
  clear. 
  

  

  Examination 
  revealed 
  the 
  fact 
  that 
  the 
  lithium 
  had 
  traveled 
  upward 
  a 
  distance 
  of 
  

   17 
  cm. 
  from 
  the 
  level 
  of 
  the 
  solution, 
  or 
  13 
  cm. 
  in 
  the 
  stem 
  and 
  4 
  cm. 
  in 
  the 
  roots. 
  

   Not 
  a 
  trace 
  of 
  lithium 
  could 
  be 
  found 
  in 
  the 
  roots 
  outside 
  the 
  bottle. 
  One 
  of 
  these 
  

   roots 
  joined 
  the 
  stem 
  two 
  internodes 
  below 
  the 
  highest 
  point 
  in 
  the 
  stem 
  reached 
  by 
  

   the 
  lithium. 
  As 
  the 
  lithium 
  had 
  gone 
  upward 
  only 
  13 
  cm. 
  out 
  of 
  a 
  possible 
  40 
  cm., 
  

   it 
  is 
  reasonable 
  to 
  assume 
  that 
  these 
  figures 
  approximate 
  the 
  rate 
  of 
  current 
  in 
  the 
  

   plant. 
  

  

  Mere 
  diffusion 
  will 
  not 
  account 
  for 
  these 
  results, 
  for 
  if 
  the 
  process 
  

   were 
  simply 
  that, 
  why 
  should 
  not 
  the 
  roots 
  outside 
  the 
  bottles 
  have 
  at 
  

   least 
  a 
  trace 
  of 
  lithium 
  in 
  the 
  portion 
  close 
  to 
  the 
  stem 
  axis 
  in 
  which 
  

   the 
  salt 
  was 
  present 
  in 
  abundance 
  ? 
  Mere 
  diffusion 
  of 
  salts 
  takes 
  place 
  

   more 
  rapidly 
  downward 
  than 
  upward, 
  

  

  MEASUREMENT 
  OF 
  ROOT 
  ABSORPTION. 
  

  

  RANUNCULUS 
  AQUATILIS 
  TRICHOPHYLLUS. 
  

  

  Experiment 
  No. 
  16. 
  — 
  This 
  was 
  performed 
  in 
  the 
  greenhouse 
  in 
  March. 
  By 
  this 
  

   method 
  the 
  amount 
  of 
  water 
  absorbed 
  by 
  the 
  root 
  is 
  measured 
  directly. 
  The 
  root 
  

   is 
  inclosed 
  in 
  a 
  bottle 
  (figure 
  6) 
  provided 
  with 
  an 
  indicating 
  tube 
  in 
  which 
  the 
  

   water 
  level 
  falls 
  as 
  absorption 
  by 
  the 
  root 
  proceeds. 
  K. 
  very 
  simple 
  preparation 
  

   proved 
  adequate 
  for 
  this 
  purpose. 
  A 
  rubber 
  stopper 
  was 
  pierced 
  with 
  a 
  steel 
  wire 
  

   and 
  the 
  projecting 
  end 
  of 
  the 
  wire 
  heated 
  until 
  the 
  rubber 
  melted 
  to 
  form 
  a 
  perfora- 
  

   tion 
  of 
  the 
  desired 
  diameter. 
  The 
  stopper 
  was 
  then 
  divided 
  under 
  water 
  with 
  a 
  

   sharp 
  razor, 
  a 
  very 
  smooth 
  cut 
  being 
  absolutely 
  necessary. 
  The 
  accompanying 
  figure 
  

   shows 
  the 
  plan 
  of 
  the 
  apparatus. 
  The 
  indicating 
  tube 
  rises 
  above 
  the 
  level 
  of 
  the 
  

   water 
  in 
  the 
  aquarium 
  and 
  descends 
  to 
  the 
  level 
  of 
  the 
  stopper's 
  base, 
  so 
  that 
  air 
  

   bubbles 
  may 
  have 
  an 
  easy 
  exit. 
  

  

  