334 
North  American  Conifer ce. 
Am.  Jour.  Pbarm, 
June,  1896. 
MICROSCOPICAL  STRUCTURE. 
A  cross-section  of  the  leaf  showed  a  thick-walled  rather  small- 
celled  epidermis,  supported  by  a  usually  one-layered  hypoderma 
composed  of  cells  with  moderately  thickened  walls.    The  secretion 
4 
Fig.  36,  cross-section  of  leaf  of  Pinus  sylvestris,  magnified  about  90  diame- 
ters. St,  stoma  ;  sec.  r.,  secretion  reservoir  ;  f,  fibres,  very  thick- walled,  adja- 
cent to  the  bast;  ph,  phloem  of  a  bundle;  en,  endodermis;  f,  fibres;  t,  trans- 
fusion tissue,  consisting  of  short,  pitted  tracheids. 
