﻿ROOTS 
  AND 
  THEIK 
  KELATIOiV 
  TO 
  PLANTS 
  

  

  together 
  with 
  the 
  minute 
  sub-division 
  of 
  the 
  epidermis 
  from 
  

   which 
  it 
  springs 
  (fig. 
  16, 
  e), 
  furnishes 
  a 
  good 
  example 
  of 
  one 
  

   kind 
  of 
  plant 
  cell. 
  1 
  Each 
  live 
  root 
  hair 
  consists 
  of 
  an 
  ex- 
  

   tremely 
  thin 
  sac, 
  the 
  cell 
  wall 
  (shown 
  in 
  figs, 
  6 
  and 
  16 
  

   merely 
  as 
  a 
  continuous 
  line 
  bounding 
  the 
  root 
  hairs), 
  and 
  the 
  

   living 
  contents 
  of 
  the 
  cell, 
  known 
  as 
  the 
  jn-ti>laxt. 
  The 
  cell 
  

   wall 
  consists 
  of 
  a 
  material 
  known 
  as 
  cclliilnxe, 
  familiar 
  to 
  all 
  

   in 
  the 
  microscopic 
  

   fibers 
  of 
  cotton. 
  The 
  

   cell 
  contents, 
  or 
  pro- 
  

   toplast, 
  of 
  a 
  root 
  hair 
  

   consists 
  largely 
  of 
  

   a 
  nearly 
  transparent 
  

   portion, 
  the 
  cytoplasm, 
  

   composed 
  of 
  nitroge- 
  

   nous 
  material 
  which 
  

   may 
  be 
  roughly 
  com- 
  

   pared 
  to 
  very 
  thin 
  

   white 
  of 
  egg. 
  Within 
  

  

  FIG. 
  16. 
  Cells 
  from 
  the 
  surface 
  of 
  a 
  young 
  rootlet 
  

   Showing 
  epidermal 
  cells 
  (e) 
  and 
  one 
  young 
  and 
  two 
  

  

  the 
  cytoplasm 
  are 
  older 
  root 
  hairs 
  (7i). 
  In 
  the 
  root 
  hairs 
  the 
  nucleus 
  

  

  found 
  111 
  ailV 
  Some- 
  ('*) 
  anc 
  ^ 
  S 
  raim 
  l 
  ar 
  cytoplasm 
  of 
  the 
  Cells 
  are 
  shown. 
  

  

  Greatly 
  magnified. 
  After 
  Bonnier 
  and 
  Sahlon 
  

  

  what 
  opaque 
  and 
  

  

  very 
  minute 
  particles, 
  also 
  rather 
  large, 
  clear 
  spaces 
  consist- 
  

   ing 
  of 
  very 
  watery 
  cell 
  sap, 
  and 
  a 
  structure 
  less 
  transparent 
  

   than 
  the 
  cytoplasm, 
  known 
  as 
  the 
  nucleus 
  (fig. 
  16, 
  ri). 
  

  

  Other 
  cells, 
  of 
  more 
  complicated 
  constitution 
  than 
  root 
  

   hairs, 
  often 
  contain 
  many 
  other 
  structures 
  and 
  materials 
  

   besides 
  those 
  here 
  mentioned. 
  Some 
  of 
  these 
  are 
  briefly 
  

   discussed 
  and 
  figured 
  in 
  Chapter 
  IV. 
  

  

  18. 
  The 
  work 
  of 
  cells. 
  The 
  simplest 
  plants, 
  as 
  will 
  be 
  shown 
  

   later, 
  consist 
  of 
  a 
  single 
  cell 
  each. 
  Every 
  ordinary 
  flowering 
  

  

  1 
  The 
  student 
  will 
  find 
  many 
  Illustrations 
  of 
  different 
  types 
  of 
  cells 
  in 
  

   later 
  chapters. 
  Some 
  very 
  simple 
  ones 
  are 
  discussed 
  in 
  Chapter 
  XV. 
  Many 
  

   cells 
  of 
  the 
  lower 
  forms 
  of 
  plant 
  life 
  are 
  much 
  more 
  easily 
  studied 
  than 
  the 
  

   colorless 
  and 
  nearly 
  transparent 
  root 
  hairs. 
  The 
  minute 
  anatomy 
  of 
  the 
  

   cell 
  is 
  most 
  easily 
  studied 
  in 
  cells 
  which 
  exist 
  as 
  separate 
  individuals 
  and 
  

   which 
  have 
  among 
  their 
  contents 
  some 
  colored 
  structures. 
  

  

  