﻿MacDougal: 
  Growth 
  of 
  the 
  tomato 
  267 
  

  

  Regardless 
  of 
  other 
  causes 
  the 
  acidity, 
  high 
  salt 
  content 
  and 
  

   low 
  albumin 
  content 
  would 
  be 
  sufficient 
  to 
  restrict 
  absorption 
  of 
  

   water 
  by 
  the 
  plasmatic 
  colloids 
  to 
  two 
  thirds 
  the 
  capacity 
  shown 
  

   by 
  young 
  fruits. 
  

  

  If 
  we 
  now 
  turn 
  to 
  cultural 
  experiments, 
  ample 
  confirmation 
  

   IS 
  found 
  for 
  the 
  conclusion 
  that 
  the 
  amino-compounds 
  which 
  

   increase 
  hydration 
  or 
  water 
  absorption 
  also 
  facilitate 
  or 
  accelerate 
  

   growth 
  as 
  measured 
  in 
  terms 
  of 
  dry 
  weight, 
  as 
  found 
  by 
  Dach- 
  

   nowski 
  and 
  Gormley, 
  Borowicov, 
  Long, 
  and 
  Schreiner, 
  Skinner 
  

   and 
  Beattie,* 
  

  

  Still 
  one 
  more 
  feature 
  of 
  growth 
  remains 
  to 
  be 
  considered, 
  

   that 
  of 
  certain 
  retarding 
  factors. 
  The 
  material 
  which 
  goes 
  to 
  

   increase 
  the 
  fruit 
  of 
  the 
  tomato 
  is 
  about 
  90 
  per 
  cent 
  water. 
  As 
  

   water 
  is 
  being 
  constantly 
  transpired 
  from 
  the 
  thin 
  skins 
  of 
  these 
  

   fruits, 
  it 
  is 
  obvious 
  that 
  a 
  hightened 
  transpiration 
  might 
  throw 
  

   off 
  water 
  at 
  a 
  rate 
  which 
  would 
  use 
  much 
  of 
  the 
  liquid 
  brought 
  in 
  

   by 
  absorption 
  and 
  thus 
  decrease 
  growth. 
  This 
  occurs 
  almost 
  

   every 
  day 
  of 
  sunshine 
  and 
  may 
  result 
  in 
  the 
  fruit 
  having 
  a 
  lesser 
  

   diameter 
  at 
  noon 
  than 
  at 
  sunrise. 
  Such 
  cessation 
  of 
  growth 
  in 
  

   length 
  and 
  thickness 
  of 
  stems 
  has 
  been 
  observed 
  many 
  times, 
  

   and 
  was 
  earlier 
  supposed 
  to 
  be 
  due 
  to 
  the 
  retarding 
  action 
  of 
  light. 
  

   It 
  is 
  however 
  simply 
  a 
  loss 
  of 
  water 
  greater 
  than 
  the 
  absorption 
  

  

  during 
  the 
  same 
  time 
  with 
  a 
  consequent 
  shrinkage. 
  

  

  The 
  principal 
  conclusions 
  supported 
  by 
  the 
  foregoing 
  may 
  be 
  

  

  briefly 
  stated 
  as 
  follows 
  : 
  

  

  I. 
  The 
  fruits 
  of 
  the 
  tomato 
  {Lycopersictim) 
  furnish 
  examples 
  

   of 
  development 
  and 
  growth 
  without 
  increase 
  of 
  dry 
  weight. 
  

  

  * 
  See 
  MacDougal. 
  D. 
  T, 
  Hydration 
  and 
  growth. 
  Carnegie 
  Inst. 
  Washington 
  

   Publ. 
  No. 
  297, 
  1920. 
  See 
  pp. 
  51 
  and 
  52, 
  63 
  and 
  64, 
  and 
  the 
  following 
  titles 
  not 
  

   considered 
  in 
  the 
  preparation 
  of 
  that 
  publication: 
  

  

  Schreiner. 
  C, 
  J. 
  J. 
  Skinner. 
  Specific 
  action 
  of 
  organic 
  compounds 
  in 
  modifying 
  

   plant 
  characteristics; 
  methyl 
  glycocoll 
  versus 
  glycocoll. 
  Bot. 
  Gaz. 
  59: 
  445-463. 
  

  

  1915. 
  

  

  Skinner, 
  J, 
  J., 
  & 
  J. 
  H. 
  Beattie. 
  Effect 
  of 
  asparagin 
  on 
  absorption 
  and 
  growth 
  

  

  in 
  wheat. 
  Bull. 
  Torrey 
  Club 
  39: 
  429-437. 
  P^- 
  33- 
  1912. 
  (Good 
  account 
  of 
  previous 
  

  

  work 
  with 
  asparagin.) 
  - 
  

  

  Shreiner, 
  O.. 
  & 
  J. 
  J. 
  Skinner. 
  Experimental 
  study 
  of 
  the 
  effect 
  of 
  some 
  nitro- 
  

   genous 
  soil 
  constituents 
  on 
  growth. 
  Nucleic 
  acid 
  and 
  its 
  decomposition 
  products. 
  

  

  Plant 
  World 
  16: 
  45-60. 
  19 
  13. 
  

  

  Borowicov, 
  G. 
  A. 
  On 
  the 
  action 
  of 
  different 
  substances 
  on 
  the 
  velocity 
  of 
  growth 
  

  

  of 
  vegetables. 
  Publ. 
  Soc. 
  Nat. 
  New 
  Russia 
  41: 
  i5-i94. 
  1916. 
  

  

  