322 
Nor tli  American  Conifer  ce. 
Am.  Jour.  Pharm 
June.  1896. 
conic-ovate,  about  2  inches  long  and  with  but  slightly  thickened, 
pointless  scales.  The  leaves  are  5  or  6  inches  long,  in  twos,  from 
long  sheaths,  convex  on  one  side  and  flat  on  the  other,  the  former 
with  from  eight  to  twelve  rows  of  stomata,  and  the  latter  with  from 
seven  to  ten  rows.  Hypoderma  often  only  one-layered  or  two- 
layered  only  in  places ;  the  single  layer,  or  where  doubled,  the  outer 
one,  composed  of  cells  which  are  only  moderately  thick-walled, 
while  the  cells  of  the  inner  layer  are  excessively  thick- walled. 
Secretion  reservoirs  numerous,  from  nine  to  twelve,  located  next 
the  hypoderma,  and  each  is  bounded  by  a  layer  of  thick-walled 
Fig.  28,  cross-section  of  leaf  of  Pinus  resinosa,  magnified  about  100  diameters. 
St,  stoma  ;  f,  band  of  fibrous  tissue  forming  the  outer  boundary  of  the  bast ; 
sec.  r,,  secretion  reservoir. 
cells.  The  fibro-vascular  bundles  are  each  crossed  by  three  or  four 
medullary  rays.  A  band  of  thick-walled  fibres  in  about  two  rows 
bounds  the  bast  on  its  exterior  and  extends  across  the  interval 
between  the  bundles.  There  are  usually  also  a  few  thick-walled 
fibres  forming  an  interrupted  row  opposite  the  xylem  ends  of  the 
bundles. 
MICROSCOPICAL  STRUCTURE. 
A  cross-section  of  a  branch  of  two  years'  growth  showed  the  fol- 
lowing structure  :  Externally,  an  epidermis,  in  places  ruptured, 
composed  of  small,  but  excessively  thick-walled  cells  ;  beneath  this 
two  or  three  layers  of  thin-walled  parenchyma,  interior  to  which  was 
