Fig.  22,  portion  of  cross-section  of  stem  of  two  years'  growth  of  Pinus 
Cubensis,  magnified  100  diameters.  A,  disintegrating  tissues  at  exterior  ;  6, 
sclerotic  cells  of  periderm  ;  c,  tannin  cell  of  cortex  \  d,  secretion  reservoir  in 
cortex  ;  <?,  bast  layer  ;  f,  cambium  ;  g,  tracheids  of  secondary  xylem. 
