304 BOTANICAL GAZETTE [may 
the vertical and the horizontal plane, while in Abies they occur only 
in the vertical plane. Moreover, resin canals occasionally occur 
in the xylem of the cone in Cedrus, but not in Abies. 
The foregoing facts go to show that Cedrus is in many respects 
intermediate between Pinus and Abies. That Abies stands farther 
Fic. 7.—C. atlantica, stem; at the junction of two growth rings a row of resin 
cells forms a continuation of a marginal cell of the ray; 425. 
down than Cedrus in this reduction series is indicated by the fact 
that it is mostly in connection with wounds that marginal paren- 
chyma occurs in Abies, while such cells occur normally in Cedrus. 
The following evolutionary stages in ray structure are indicated: 
1. Medullary rays typically provided with marginal row of cells, 
which are tracheids: Pinus, Picea. 
