﻿I 
  

  

  The 
  physical 
  factors 
  in 
  the 
  growth 
  of 
  the 
  tomato 
  

  

  D. 
  T. 
  MacDougal 
  

  

  The 
  tissues 
  of 
  animals 
  and 
  of 
  the 
  greater 
  number 
  of 
  plants 
  

   accumulate 
  carbohydrates, 
  proteins, 
  salts 
  and 
  other 
  solids 
  during 
  

   the 
  course 
  of 
  growth 
  in 
  such 
  manner 
  that 
  the 
  relative 
  dry 
  weight 
  

   of 
  an 
  organ 
  is 
  least 
  in 
  the 
  embryonic 
  or 
  earlier 
  stages, 
  and 
  in- 
  

   creases 
  progressively 
  so 
  that 
  the 
  proportion 
  of 
  solid 
  material 
  is 
  

   highest 
  and 
  of 
  water 
  is 
  lowest 
  at 
  maturity. 
  

  

  The 
  stems 
  and 
  leaves 
  of 
  succulents 
  and 
  such 
  berry-like 
  fruits 
  

   as 
  the 
  tomato 
  {Ly 
  coper 
  sicum) 
  have 
  been 
  found 
  to 
  reverse 
  this 
  

   relation,* 
  and 
  melons, 
  mushrooms 
  and 
  similar 
  structures 
  probably 
  

   do 
  the 
  same. 
  

  

  Tomatoes 
  14-18 
  mm. 
  in 
  diameter 
  grown 
  at 
  the 
  Coastal 
  Labor- 
  

   atory, 
  Carmel, 
  California, 
  were 
  found 
  to 
  contain 
  but 
  87 
  per 
  cent 
  

   of 
  water, 
  while 
  mature 
  fruits 
  consisted 
  of 
  91 
  per 
  cent 
  water 
  and 
  

   9 
  per 
  cent 
  solid 
  material. 
  An 
  analysis 
  by 
  Albahary 
  gave 
  93.63 
  

   per 
  cent 
  of 
  water 
  in 
  young 
  tomatoes 
  and 
  94.3 
  per' 
  cent 
  in 
  ripe 
  

  

  fruits. 
  t 
  

  

  In 
  addition 
  to 
  the 
  measurements 
  already 
  published, 
  it 
  seems 
  

   desirable 
  to 
  give 
  the 
  data 
  secured 
  in 
  1919, 
  to 
  make 
  further 
  compar- 
  

   isons 
  between 
  the 
  apparent 
  growth 
  as 
  found 
  by 
  the 
  increase 
  in 
  the 
  

   diameter 
  of 
  the 
  fruits, 
  and 
  to 
  record 
  the 
  actual 
  increase 
  in 
  volume,? 
  

   and 
  to 
  formulate 
  an 
  explanation 
  of 
  growth 
  based 
  upon 
  the 
  osmotic 
  

   and 
  colloidal 
  action 
  of 
  the 
  plasmatic 
  substances 
  under 
  the 
  in- 
  

   fluence 
  of 
  cell-sap 
  of 
  varying 
  composition. 
  

  

  Vigorous 
  plants 
  bearing 
  fruits 
  in 
  all 
  stages 
  were 
  available 
  in 
  

   August 
  and 
  September, 
  1919, 
  and 
  suit 
  able 
  stages 
  were 
  erected 
  

  

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

   No. 
  297. 
  1920. 
  See 
  especially 
  pages 
  166-172. 
  Also. 
  Hydration 
  and 
  growth, 
  

  

  Proc. 
  Amer. 
  Phil. 
  Soc. 
  58: 
  346-373- 
  I9i9- 
  

  

  t 
  Albahary, 
  F. 
  M 
  . 
  Etude 
  chimique 
  de 
  la 
  maturation 
  du 
  Lycoperstaim 
  esculenlum 
  

  

  (Tomate). 
  Compt. 
  Rend. 
  Acad. 
  Sci. 
  Paris, 
  147: 
  146-147. 
  1908. 
  

  

  t 
  Note 
  In 
  a 
  discussion 
  of 
  this 
  subject 
  in 
  the 
  Proc. 
  Amer. 
  Phil. 
  Soc. 
  58: 
  367. 
  

   I9ii 
  the 
  formula 
  for 
  obtaining 
  the 
  volume 
  of 
  a 
  sphere, 
  4/3 
  (PiR') 
  was 
  erroneously 
  

  

  given 
  as 
  (PiR^). 
  

  

  261 
  

  

  