Am.  Jour.  Pharm. 
July,  1880. 
Structure  of  Dye-Woods, 
J5J 
low  color.  The  naked  eye  will  detect  on  the  cross  section  a  regular 
yellow  background,  in  which  are  imbedded  strongly  converging,  very 
broad,  light  yellow  medullary  rays.  All  of  the  latter  are  distinct.  The 
ducts  appear  as  small  dark  points,  which  are  partly  regularly  distributed 
over  the  cross  section,  partly  disposed  in  cross  bands.  Under  the  lens, 
the  ducts  are  found  to  be  empty,  and  nothing  more  is  noticeable  except 
what  the  eye  would  detect.  The  width  of  medullary  rays  on  the  cross 
section  sometimes  increases,  and  sometimes  the  opposite  occurs.  The 
annual  rings  are  visible,  but  not  so  distinct  as  in  the  other  yellow- 
woods.  On  the  tangent  section  the  medullary  rays  occur  as  nearly 
obliterated,  broad  longitudinal  lines,  the  ducts  as  very  thin  dark  lines. 
On  the  radial  section  the  medullary  rays  appear  over  2  mm.  wide,  and 
are  furnished  with  horizontal  lines. 
8.  Rhus  Cotinus, — In  a  cross  section  the  naked  eye  will  perceive  con- 
centric light  and  dark  cross  bands.  The  ducts  appear  as  small  points, 
and  the  medullary  rays  are  only  indicated.  Oq  the  tangent  section  the 
ducts  are  noticed,  in  an  ochre-yellow  ground,  as  light  brown  longitu- 
dinal lines.  On  the  radial  section  the  very  small  medullary  rays  occur 
rarely  ;  the  ducts  appear  as  on  the  tangent  section.  Fig.  10  represents 
the  cross  section,  under  the  lens.  The  fine  medullary  rays  are  only 
partially  visible.  The  very  narrow  ducts  are  disposed  in  radial  series 
and  the  entire  wood  fibre  split  up  into  brown,  compact,  ductless  zones, 
and  into  yellow,  porous,  concentric  layers,  full  of  ducts.  On  the  lon- 
gitudinal sections  the  ducts  appear  complete  and  very  lustrous,  while 
the  medullary  rays  are  rare  on  the  radial  section.  They  are  darker 
than  the  base,  just  as  in  the  tangent  section,  where  they  appear  as  very 
minute,  pale  brown  longitudinal  lines. 
From  what  has  been  said  I  believe  I  have  made  it  evident  that  to 
crude  organic  products  belong  a  number  of  properties  which  are  visible 
to  the  naked  eye  and  under  the  lens,  but  which  have  heretofore  been 
too  slightly  appreciated  in  considering  these  articles.  As  the  search  for 
accurately  distinguishing  features  between  raw  products,  similar  but  of 
unequal  value,  is  one  of  the  principal  ends  in  view  in  the  study  of  such 
material,  no  method  should  be  despised  in  order  to  arrive  at  the  desired 
end.  I  hope  the  preceding  communication  will  be  received  in  this 
sense. 
23 
