350  Structure  of  Dye-Woods.  {^''■XJ^o''!'' 
Ie3is  the  medullary  rays  and  annual  rings  are  not  discernible.  The 
ducts  on  the  tangential  section  appear  as  delicate,  dark,  longitudinal 
lines.  Tangential  cleavage  planes  exhibit  very  delicate  cross-lines, 
which  impart  a  wave-like  appearance  to  the  same.  They  originate 
from  the  medullary  rays  disposed  in  horizontal  lines.  The  principal 
radial  cross-section  has  a  similar  appearance.  The  medullary  rays 
are  all  small,  4  to  5=1  mm.  Fig.  4  represents  a  cross-section  under 
the  lens.  The  medullary  rays  are  equally  removed  from  each  other, 
and  almost  equally  strong.  The  annual  growths  are  recognized  as 
very  delicate  cross-lines.  The  parenchymous  spots  are  rounded  and 
not  sharply  defined.  They  contain  several  very  narrow  ducts  which, 
however,  on  a  cross-section  and  under  a  lens,  are  found  to  be  distinct 
tubes.  The  parenchymous  spots  rarely  adhere  to  each  other;  they 
never  form  tangential  separated  fascia. 
A  tangent  view  with  the  lens  shows  the  medullary  rays  as  delicate, 
short,  dark,  longitudinal  lines,  the  ducts  as  dark,  half-tubes,  and  the 
parenchyma  as  pale,  longitudinal  stripes.  Upon  both  longitudinal  views 
under  the  lens  the  wave  appearance  becomes  more  evident. 
Sapan-wood  (Fig.  5)  exhibits  on  a  cross-section  larger  parenchymous 
spots  than  the  Brazil-wood.  The  duct  cross-sections  appear  as  holes 
to  the  naked  eye.  The  annual  rings  are  distinct.  Characteristic 
paler  and  darker  concentric  fascia  are  formed  by  the  parenchymous 
spots  being  in  greater  proximitv  on  the  internal  edge  of  the  annual 
growths.  The  medullary  rays  are  just  visible  to  the  naked  eye.  The 
radial  view  does  not  disclose  a  wave  appearance,  although  the  medul- 
lary rays  are  more  distinct  than  in  the  case  of  Brazil-wood  (0*25  to 
0*66  mm.  high).  The  wave  appearance  is  not  observed  on  the  tan- 
gent cross-plane.  The  medullary  rays  appear  very  distinctly  as  short 
longitudinal  stripes,  especially  on  cleavage  surfaces.  On  both  longi- 
tudinal surfaces  the  ducts  appear  as  recognizable  half-tubes.  The  lens 
shows  the  large  duct  sections  very  plainly,  also  the  medullary  rays, 
separated  from  each  other  by  nearly  equal  spaces,  and  the  narrow 
annual  rings  looking  like  lines.  The  parenchymous  sheath  of  the 
ducts  are  relatively  smaller  than  in  the  Brazil  and  Coulteria  Redwood, 
often  barely  visible,  so  that  the  respective  ducts  appear  to  border  closely 
on  libriform.  Nothing  new  is  observed  when  viewed  longitudinally 
under  the  lens. 
4.  Red  Sandal'Wood  (Pterocarpus  santalinus),  in  cross-sections,  pre- 
