458  Contributions  from  the  School  of  Pharmacy,  etc,{^''^-?^''^^\l^^;''^' 
the  cortical  layer,  and  edges  turned  toward  the  center  of  the  plant* 
The  tissue  is  a  parenchyma  composed  of  thin-walled  cells,  somewhat 
elongated  in  the  direction  of  the  axis  of  the  root.  In  the  transverse  sec- 
tion the  outer  cells  are  flattened  and  tangential.  These  cells  gradually 
pass  into  those  of  the  medullary  rays,  which  are  flattened  at  the  sides 
and  extended  radially.  The  cells  of  the  middle  layers  contain  consid- 
erable starch.  Masses  of  orange  or  yellow  resin  also  occur  in  some 
abundance.  The  wedges  of  the  liber  or  inner  bark  are  visible  to  the 
naked  eye  as  slender,  somewhat  curved,  hyaline  rays,  broad  at  the  base, 
extending  through  the  dead-white  middle  layer.  An  amplification  of 
50  diameters  shows  these  wedges  to  be  made  up  of  alternating,  trans- 
verse rows  of  long,  slender,  very  thick-walled  liber-fibers  and  paren- 
chymatous cells.  The  wedges  are  sometimes  split  for  a  short  distance 
at  the  base  by  short  medullary  rays.  The  larger  medullary  rays,  as 
already  mentioned,  pass  insensibly  into  the  middle  layer.  They  are 
very  broad.  The  starch  is  abundant  in  the  parenchyma  of  the  middle 
layer  and  liber.  It  consists  of  roundish  grains,  about  the  size  of  the 
grains  of  corn-starch,  but  with  curved  surfaces.  They  are  usually 
simple,  though  as  many  as  six  or  eight  are  aggregated.  The  nucleus 
is  usually  visible  with  a  magnifying  power  of  50  diameters,  but  the 
rings  are  not.  The  grains  turn  blue  promptly  on  the  addition  of  iodine. 
The  resins  are  in  large  rounded  masses,  occupying  the  space  of  eight 
or  ten  absorbed  cells  in  the  parenchyma  of  the  middle  and  inner  layer. 
The  color  varies  from  yellow  to  a  deep  red,  usually  yellow-orange. 
The  masses  are  easily  seen  by  the  naked  eye,  as  dark  round  dots  in 
about  the  middle  of  the  bark.  The  masses  often  slowly  dissolve  in 
water,  setting  free  innumerable  minute  granules  which  exhibit  active 
movements,  the  characteristic  microscopic  behavior  of  a  gum-resin. 
The  wood  is  noteworthy  for  two  reasons  :  (i)  the  pith  is  always  more 
or  less  excentric  ;  (2)  the  resin  is  rarely  found  in  it." 
The  chemical  examination  was  conducted  as  follows  :  Of  the  dried 
and  powdered  bark,  100  grams  were  moistened,  macerated  in  conical 
percolator  for  three  days,  and  slowly  percolated  with  alcohol  of  specific 
gravity  0*835,  till  the  menstruum  came  through  colorless,  and  left  no 
residue  on  evaporation.  The  percolate  was  of  a  dark  brownish-red 
color  :  it  was  put  in  a  retort  and  the  alcohol  recovered.  I  he  residue 
consisted  of  a  syrupy  aqueous  solution  of  pale  red  color,  and  a  dark 
red  precipitate  of  resin.  The  entire  residue  was  treated  with  water, 
and  thrown  upon  a  moist  filter.  The  aqueous  filtrate  from  the  resin 
had  a  sweetish  taste,  and  when  warmed  with  potassio-cupric  tartrate. 
