﻿4 
  

  

  Miller: 
  The 
  wood 
  of 
  Machaerium 
  Whitfordii 
  79 
  

  

  Chambered 
  parenchyma 
  strands, 
  with 
  eight 
  toTourteen 
  cr>^stal- 
  

   bearing 
  cells 
  per 
  strand, 
  are 
  common. 
  The 
  crystals 
  (Fig. 
  7) 
  are 
  

   rhombohedral, 
  measuring 
  about 
  10 
  ju 
  high 
  and 
  7.5 
  /x 
  wide. 
  They 
  

   appear 
  to 
  be 
  surrounded 
  by 
  a 
  gelatinous 
  coat 
  or 
  layer, 
  which 
  may 
  

   protect 
  them 
  to 
  some 
  extent 
  from 
  the 
  action 
  of 
  nitric 
  acid, 
  since 
  - 
  

   they 
  are 
  found 
  in 
  macerated 
  material. 
  

  

  Rays, 
  — 
  The 
  rays 
  (Figs. 
  5 
  and 
  6), 
  as 
  seen 
  in 
  tangential 
  section, 
  

   are 
  in 
  horizontal 
  seriation, 
  uniform, 
  mostly 
  uniseriate 
  (occasionally 
  

   biseriate 
  in 
  part), 
  and 
  from 
  eight 
  to 
  twelve 
  cells 
  high. 
  They 
  

   measure 
  0.9-0.15 
  mm. 
  in 
  height 
  and 
  about 
  15 
  /x 
  in 
  width 
  at 
  the 
  

  

  median 
  portion. 
  

  

  In 
  radial 
  section 
  the 
  rays 
  (Fig. 
  8) 
  are 
  homogeneous, 
  and 
  the 
  

   cells 
  are 
  rectangular, 
  0.075-0.087 
  mm. 
  in 
  length 
  and 
  about 
  12.5 
  n 
  

   high. 
  The 
  marginal 
  cells 
  are 
  regular 
  in 
  form 
  and 
  procumbent 
  

   like 
  the 
  others 
  making 
  up 
  the 
  ray. 
  The 
  walls 
  between 
  adjacent 
  

   ray 
  cells 
  are 
  finely 
  and 
  abundantly 
  pitted. 
  The 
  lateral 
  walls, 
  

   where 
  in 
  contact 
  with 
  vessels, 
  exhibit 
  numerous 
  small 
  bordered 
  

   pits 
  (structurally 
  half-bordered), 
  which 
  are 
  arranged 
  in 
  two 
  

   horizontal 
  rows, 
  one 
  or 
  two 
  to 
  each 
  cell. 
  The 
  mouth 
  of 
  the 
  pit 
  is 
  

   narrowly 
  lenticular 
  and 
  the 
  membrance 
  disiintly 
  perforated. 
  

   In 
  the 
  heartwopd 
  the 
  ray 
  cells 
  are 
  very 
  gummy, 
  the 
  gum 
  being 
  

   collected 
  at 
  the 
  cross 
  walls 
  between 
  cells, 
  or 
  along 
  the 
  inner 
  side 
  

   of 
  the 
  cell 
  wall. 
  

  

  Summary 
  

  

  I. 
  Machaerium 
  Whitfordii 
  is 
  a 
  species 
  of 
  Colombian 
  tree 
  

  

  MacBride 
  

  

  true 
  

  

  rosewoods, 
  appears 
  to 
  have 
  good 
  cabinet 
  qualities, 
  and 
  is 
  of 
  com- 
  

   merical 
  importance. 
  The 
  specific 
  gravity 
  of 
  the 
  heartwood 
  

  

  dry) 
  

  

  very 
  

  

  variegated 
  color, 
  the 
  fine 
  lines 
  of 
  terminal 
  parenchyma, 
  the 
  storied 
  

   arrangement 
  of 
  its 
  elements 
  "(including 
  localized 
  pit 
  areas 
  on 
  the 
  

   fibers), 
  its 
  homogeneous 
  and 
  usually 
  uniseriate 
  rays, 
  the 
  presence 
  of 
  

   -small 
  half-bordered 
  pits 
  between 
  vessels 
  and 
  ray 
  cells, 
  and 
  the 
  

   sieve-like 
  perforations 
  of 
  the 
  pit 
  membrane. 
  

  

  Acknowledgment 
  is 
  made 
  to 
  Professor 
  Samuel 
  J, 
  Record 
  of 
  

   Yale 
  University, 
  under 
  whose 
  direction 
  this 
  study 
  was 
  made, 
  

   and 
  also 
  to 
  Dr. 
  Forest 
  B. 
  H. 
  Brown 
  for 
  assistance 
  in 
  technique. 
  

  

  University 
  of 
  Illinois, 
  

  

  