﻿Miller: 
  The 
  wood 
  of 
  Machaerium 
  Whitfordii 
  75 
  

  

  Growth 
  rings 
  (FiG. 
  l), 
  which 
  presumably 
  do 
  not 
  correspond 
  to 
  

   annual 
  periods, 
  are 
  visible 
  and 
  are 
  demarcated 
  by 
  terminal 
  wood 
  

  

  r 
  

  

  parenchyma 
  which 
  forms 
  a 
  single 
  or 
  sometimes 
  double 
  or 
  triple 
  line. 
  

   These 
  rings 
  exhibit 
  considerable 
  variation 
  in 
  width. 
  The 
  pores 
  

   are 
  numerous, 
  solitary 
  or 
  in 
  small 
  groups 
  (usually 
  radial), 
  diffused 
  

  

  r 
  

  

  irregularly 
  throughout 
  the 
  ring 
  or, 
  occasionally, 
  in 
  echelon 
  arrange- 
  

   ment. 
  They 
  are 
  of 
  fairly 
  uniform 
  size 
  throughout 
  and 
  are 
  barely 
  

   visible 
  to 
  the 
  unaided 
  eye. 
  

  

  » 
  The 
  rays 
  are 
  not 
  visible 
  on 
  the 
  cross 
  section 
  without 
  a 
  lens. 
  

   They 
  are 
  numerous, 
  fine 
  and 
  uniform. 
  On 
  the 
  tangential 
  section 
  

   they 
  are 
  seen 
  (under 
  the 
  lens) 
  to 
  be 
  of 
  equal 
  height 
  and 
  arranged 
  

   In 
  horizontal 
  senation, 
  thus 
  giving 
  rise 
  to 
  fine 
  and 
  uniform 
  trans- 
  

   verse 
  lines, 
  the 
  so-called 
  ''ripple 
  marks," 
  which, 
  in 
  proper 
  light, 
  

   may 
  be 
  seen 
  with 
  the 
  unaided 
  eye. 
  

  

  The 
  bark 
  of 
  the 
  specimen 
  studied 
  Is 
  1.5-2 
  mm, 
  in 
  thickness 
  

   and 
  Is 
  composed 
  of 
  numerous 
  fine 
  uniform 
  concentric 
  laminations. 
  

   The 
  outer 
  surface 
  is 
  of 
  a 
  grayish 
  brown 
  color, 
  finely 
  granular, 
  

   smoothlsh, 
  with 
  occasional 
  small 
  flakes. 
  The 
  inner 
  surface 
  is 
  

   somewhat 
  ribbed 
  vertically 
  to 
  correspond 
  with 
  the 
  small 
  irregu- 
  

   larities 
  on 
  the 
  outer 
  face 
  of 
  the 
  wood, 
  and 
  exhibits 
  ''ripple 
  marks" 
  

   very 
  distinctly 
  under 
  the 
  lens. 
  

  

  0-0 
  

  

  Minute 
  anatomy 
  

  

  Vessels.— 
  The 
  vessels 
  in 
  cross 
  section 
  (pores) 
  are 
  circular, 
  

   elliptical 
  or 
  oval 
  in 
  shape; 
  some 
  of 
  them, 
  as 
  a 
  result 
  of 
  crowding 
  in 
  

   groups, 
  appear 
  to 
  be 
  subdivided 
  radially 
  (FiG. 
  2). 
  When 
  ellip- 
  

   tical, 
  the 
  tangential 
  diameter 
  is 
  0.075-0.09 
  mm. 
  and 
  the 
  radial 
  

  

  12 
  mm. 
  The 
  thickness 
  of 
  the 
  walls 
  varies 
  from 
  3 
  m 
  to 
  15 
  fi, 
  

  

  The 
  vessels 
  are 
  without 
  tyloses. 
  Gummy 
  contents, 
  which 
  are 
  

   Hght-coloied 
  and 
  not 
  very 
  pronounced 
  in 
  the 
  sapwood, 
  are 
  dark 
  

   brown 
  and 
  conspicuous 
  in 
  the 
  heartwood, 
  often 
  completely 
  filling 
  

   entire 
  segments. 
  This 
  material 
  is 
  sparingly 
  soluble 
  in 
  hot 
  water 
  

   and 
  Insoluble 
  In 
  alcohol, 
  though 
  shrinking 
  slightly 
  upon 
  dehy- 
  

   dration. 
  It 
  appears 
  unaffected 
  by 
  hydrofluoric 
  acid. 
  

  

  The 
  vessel 
  segments 
  are 
  mostly 
  straight, 
  with 
  slight 
  constric- 
  

   tions 
  at 
  each 
  end, 
  the 
  perforations 
  are 
  simple, 
  the 
  annular 
  ridge 
  is 
  

   narrow, 
  and 
  the 
  plane 
  of 
  contact 
  is 
  horizontal 
  or 
  slightly 
  oblique. 
  

   The 
  segments 
  are 
  of 
  nearly 
  uniform 
  length, 
  mostly 
  0.20-0.21 
  mm., 
  

   and 
  are 
  arranged 
  in 
  horizontal 
  seriatlon. 
  

  

  