Am.  Jour.  Pharru.  1 
October,  1896.  ) 
North  American  Conifer cb. 
555 
filled  with  oleoresin,  some  large  mucilage  sacs  irregularly  distribu- 
ted, and  numerous  parenchyma  cells  of  relatively  small  size,  most 
of  them  containing  tannin.  There  were  also  in  the  outer  portion 
of  the  middle  bark  a  few  stone  cells,  either  isolated  or  in  clusters  of 
Fig.  46. — Portion  of  cross-section  of  stem  of  Abies  balsamea,  magnified  75 
diameters.  Epy  portion  of  remaining  epidermis  ;  sec.  r.,  one  of  the  resin  pas- 
sages in  the  middle  bark  ;  t,  a  tannin  cell  in  middle  bark  ;  m.  c,  mucilage 
cell  ;  b,  band  of  tannin  cells  in  bast  layer  ;  c,  cambium  zone  ;  xy,  xylem  con- 
taining medullary  ray  cells  and  discigerous  tracheids. 
a  few.  The  inner  or  bast  layer  consisted  mostly  of  small  cells 
arranged  in  radial  rows.  The  tannin  cells  of  this  layer  were  of 
larger  size  than  the  cells  of  the  adjacent  tissues,  and  were  arranged 
