Am.  Jour.  Pharm.  1 
February,  1896.  J 
North  American  Coniferce. 
69 
At  the  exterior  the  strongly  cutinized  and  somewhat  lignified  epi- 
dermis may  still  persist,  supported  underneath  by  collenchyma.  At  a 
depth  of  several  layers  of  cells  underneath  the  epidermis,  there  was 
found  a  phellogen,  which  gave  rise  to  layers  of  stone  and  cork  cells. 
Interior  to  this  was  the  ordinary  cortical  parenchyma,consisting  mostly 
of  rather  large,  thin-walled  cells,  which  were  tangentially  elongated. 
This  region  contained  secretion  reservoirs,  which  appeared  round  or 
elliptical  in  cross- section,  but  were  seen  in  longitudinal  section  to 
form  long  tubes.  There  were  in  this  portion  of  the  cortex  few,  if 
any,  lignified  elements.  The  older  portion  of  the  bast  layer  con- 
sisted for  the  most  part  of  collapsed  and  ill-defined  sieve  elements. 
In  the  newer  bast  the  walls  of  the  individual  sieve  tubes  were  well 
defined,  but  the  cells  were  of  small  diameter.  Scattered  among 
the  sieve  tubes  were  cells  of  larger  diameter,  mostly  containing  secre- 
tions, some  oleoresin,  others  apparently  mucilage.  The  wood  had 
substantially  the  same  structure  as  that  already  described  in  Pinus 
Strobus. 
Oleoresinous  matters  abounded  not  only  in  the  secretion  reservoirs 
of  the  bark  and  wood  and  in  the  secretion  cells  about  them,  but  in 
many  scattered  cells  of  the  cortical  and  bast  layers,  in  some  of  the 
medullary  ray  cells,  and  even  in  some  of  the  tracheids  of  the  xylem. 
Tannin  was  abundant  in  the  bark,  in  all  parts  of  it  and  in  the  cam- 
bium. It  also  occurred,  though  less  abundantly,  in  the  xylem, 
particularly  in  the  secreting  cells  about  the  resin  tubes  and  in  the 
medullary  rays.  The  distribution  was,  in  fact,  similar  to  that 
already  described  in  Pinus  Strobus,  though  the  latter  species 
appeared  to  contain  considerably  less  of  it.  The  drawing  (Fig.  g) 
was  made  from  a  section  which  had  been  treated  with  a  solution  of 
ferric  chloride  in  absolute  alcohol.  The  color  of  the  precipitate  was 
greenish  black. 
CHEMICAL  COMPOSITION. 
The  leaves  of  Pinus  rigida  were  not  examined  chemically,  because 
at  present  they  possess  no  apparent  economic  value.  As  pointed 
out  in  the  preceding  description  of  the  microscopical  characters,  the 
oleoresin  is  the  most  abundant  constituent  of  the  bark.  Tannin 
was  also  found  to  be  present  in  creditable  amount,  but  mucilage  was 
found  in  much  smaller  proportion  than  in  P.  Strobus,  A  sample  of 
the  stem  bark,  collected  in  November,  yielded  the  following  per- 
centages of  astringent  principle : 
