﻿Brown: 
  Silicious 
  skeleton 
  

  

  419 
  

  

  conditions 
  would 
  tend 
  to 
  remain 
  of 
  constant 
  length, 
  though 
  the 
  

  

  water 
  content 
  of 
  the 
  matrix 
  might 
  vary 
  considerably. 
  With 
  the 
  

   application 
  of 
  force, 
  however, 
  the 
  rods 
  would 
  shorten 
  or 
  lengthen 
  

   within 
  the 
  elastic 
  limits 
  of 
  the 
  material 
  of 
  which 
  they 
  are 
  composed- 
  

   Under 
  high 
  temperatures 
  the 
  

   rods 
  appear 
  to 
  undergochange 
  

   in 
  composition, 
  possibly 
  giving 
  

   off 
  moisture, 
  and 
  may 
  then 
  be 
  

   observed 
  to 
  contract 
  in 
  length. 
  

  

  h. 
  Colloidal 
  matrix 
  

  

  The 
  material 
  in 
  which 
  the 
  

   skeleton 
  rods 
  are 
  imbedded 
  ex- 
  

   hibits 
  essentially 
  the 
  proper- 
  

   ties 
  of 
  matter 
  in 
  the 
  colloidal 
  

  

  ■ 
  

  

  state* 
  Besides 
  being 
  highly 
  

   hygroscopic 
  and 
  gelatin-like 
  

   in 
  many 
  of 
  its 
  microscopic 
  

  

  characters, 
  it 
  has 
  the 
  property 
  

   of 
  imbibing 
  methylene 
  blue 
  

   and 
  other 
  colloidal 
  solutions 
  

   even 
  in 
  the 
  living 
  condition. 
  

   The 
  term 
  colloidal 
  matrix 
  is 
  

   therefore 
  used 
  to 
  designate 
  

   that 
  portion 
  of 
  the 
  secondary 
  

   thickening 
  of 
  fibers 
  and 
  trach- 
  

   eids 
  in 
  which 
  the 
  silicious 
  

  

  skeleton 
  is 
  imbedded; 
  it 
  is 
  ap- 
  

   parently 
  stretched 
  upon 
  the 
  

   silicious 
  skeleton 
  under 
  longi- 
  

   tudinal 
  tension 
  strain- 
  This 
  is 
  ^ 
  

   indicated 
  from 
  the 
  fact 
  that 
  

  

  • 
  

  

  100 
  

  

  200 
  

  

  ± 
  

  

  SOO 
  jj 
  

  

  FiG< 
  4- 
  Isolated 
  fibers 
  of 
  Tecoma, 
  A, 
  

  

  piral! 
  

  

  after 
  a 
  macerated 
  fiber 
  of 
  Te- 
  before 
  treatment; 
  B, 
  same 
  fiber 
  after 
  de- 
  

  

  coma 
  {A, 
  Fig. 
  4) 
  has 
  remained 
  f^^'^'l''''V^^^^^ 
  t 
  

  

  a 
  few 
  minutes 
  in 
  hydrofluoric 
  

  

  acid, 
  it 
  suddenly 
  contracts 
  36 
  

  

  per 
  cent 
  or 
  more 
  longitudinally, 
  and, 
  at 
  the 
  same 
  time, 
  increases 
  

  

  often 
  as 
  much 
  as 
  100 
  oer 
  cent 
  in 
  diameter, 
  as 
  shown 
  in 
  B, 
  Fig- 
  4, 
  

  

  after 
  drying. 
  

  

  