﻿410 
  

  

  Brown: 
  Silicious 
  skeleton 
  

  

  the 
  various 
  species 
  examined, 
  the 
  wood 
  fibers 
  of 
  lapachol-forming* 
  

  

  species 
  of 
  Tecoma 
  seem 
  as 
  favorable 
  as 
  any 
  for 
  the 
  observation 
  of 
  

  

  those 
  details 
  with 
  which 
  this 
  paper 
  is 
  chiefly 
  concerned, 
  and 
  all 
  

  

  references 
  to 
  this 
  genus 
  have 
  special 
  application 
  to 
  those 
  species 
  

  

  in 
  the 
  vessels 
  of 
  which 
  the 
  sulphur-yellow, 
  monoclynic 
  crystals 
  of 
  

   lapachol 
  are 
  found. 
  

  

  1. 
  Middle 
  lamella 
  and 
  primary 
  thickening 
  

  

  In 
  an 
  unstained 
  cross-section 
  of 
  the 
  xylem 
  of 
  Tecoma 
  mounted 
  

   in 
  glycerine, 
  it 
  is 
  observed 
  that 
  the 
  middle 
  lamella 
  and 
  primary 
  

   thickenihg 
  of 
  the 
  fiber 
  (Fig. 
  i, 
  ^) 
  are 
  highly 
  refractive 
  and 
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  10 
  

  

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  e 
  

  

  30j4 
  

  

  Fig. 
  I. 
  A 
  and 
  B, 
  cross-section 
  of 
  xylem 
  of 
  Tecoma 
  sp. 
  A, 
  before 
  treatment; 
  3, 
  

   after 
  desilicification 
  and 
  drying— 
  L, 
  lumen; 
  5, 
  secondary 
  thickening; 
  T, 
  tertiary 
  

   thickening; 
  N, 
  middle 
  lamella 
  and 
  primary 
  thickening. 
  C, 
  secondary 
  thickening 
  of 
  a 
  

   single 
  tracheid, 
  showing 
  a 
  number 
  of 
  skeleton 
  rods. 
  

  

  ♦Lapachol 
  is 
  a 
  natural 
  quinone 
  dye, 
  which 
  is 
  found 
  in 
  vessels 
  of 
  the 
  heart-wood 
  

  

  South 
  

  

  It 
  forms 
  a 
  sulphur- 
  

  

  yellow 
  dust 
  over 
  the 
  cut 
  surface 
  of 
  the 
  wood 
  and, 
  when 
  moistened 
  by 
  ammonia 
  or 
  

   dilute 
  sodium 
  carbonate, 
  turns 
  deep 
  wine-red. 
  serving 
  as 
  a 
  reliable 
  character 
  in 
  the 
  

   identification 
  of 
  the 
  wood. 
  Also, 
  fine 
  chips 
  of 
  the 
  wood, 
  upon 
  standing 
  in 
  a 
  test 
  

   tube 
  partly 
  filled 
  with 
  dilute 
  aqueous 
  solution 
  of 
  sodium 
  carbonate, 
  will 
  turn 
  the 
  

   liquid 
  a 
  deepred 
  color. 
  

  

  