1918] DUFRENOY—PINE NEEDLES 447 
CS 
C7 
j 
f 
KUT 
Fic. 16 
Fics. 14-17.—Fig. 14, periderm of very 
young juvenile leaf (collected April 25, 1918): 
” ; p, phloem; y, cells of future wood beginning to lignify; g, procambium; 
rrows indicate direction of differentiation; wood first differentiates centripetally 
: : of ; 
sho j 
es; ft, foliar vascular bundles; 
proliferating spur shoot: 
bearing juvenile leaves: c', cauline vascular bu 
] 
between, also resin canals 
Al ashy ae} et NP 
n 
x, xylem; p, phloem; fig. 16, course of vascular bundles in 
xylem inside (crossed lines), phloem outside, and cambium 
and medullary rays; f', foliar bundle consisting of 2 semi-b y 
defined medullary rays; fig. 17, part of foliar bundle (f*) in needle of proliferating 
spur shoot (collected May 3, 1918), part of ft of fig. 16: ¢, cambium active and pro- 
ducing spring wood above (x) and phloem (/) below; /*, wood vessels; m*, medullary 
rays; note that revegetation begins sooner in proliferating shoots than in normal spur 
shoots, which are still dormant at this season (cf. fig. 1). 
