332 
North  American  Conifer ce. 
/Am.  Jour.  Pharm. 
\      June,  1896. 
The  xylem  showed  no  marked  peculiarities,  the  tannin  present 
being  mostly  confined  to  the  medullary  ray  cells  and  the  cells  bor- 
dering the  secretion  reservoirs. 
Fig.  33,  cross-section  of  stem,  two  years  old,  of  Pinus  Virginiana,  magnified 
85  diameters.  A,  epidermis,  composed  of  thick-walled  cells  ;  b,  tannin  cells  of 
the  cortex  ;  c,  secretion  reservoir  in  the  cortex  ;  d,  cambium  zone  ;  e,  secretion 
reservoir  in  the  xylem  ;  f,  medullary  ray  in  xylem. 
The  species  contains  considerable  oleoresin,  which  occurs  not 
only  in  the  secretion  reservoirs  and  the  secreting  cells  which  bound 
them,  but  also  in  many  of  the  tracheids  of  the  xylem  and  in  many  of 
the  ordinary  parenchyma  and  tannin-bearing  cells  of  the  bark. 
