1915] BURLINGAME—ARAUCARIA BRASILIENSIS 15 
bundles of the cotyledons the vascular cylinder is more or less 
quadrangular. The longer axis lies in the plane of the cotyledons. 
The other two sides are more weakly developed and bend in slightly 
toward the stem apex. The vascular cylinder rounds up gradually 
as it extends toward the root. 
Resin canals are abundant in the cortex of the embryo, but do 
not occur in the pith or wood. There is a fairly regular circle of 
them three or four cells beneath the epidermis. Another definite 
circle occurs just outside the procambium strands. There is no 
definite boundary between stele and cortex, and so I am somewhat 
uncertain whether this ring of ducts should be attributed to the 
cortex or to the pericycle. Some authors (20) apparently speak 
of all the outer portion of the embryo as pericycle. I can see no 
good reason for this usage. The tissue is all alike at first. Then 
the procambium strands arise in the central region, inclosing a 
region of parenchymatous cells and are in their turn surrounded 
by a similar parenchymatous region. There is a pretty regular 
correspondence in number and position between the procambium 
strands and the resin ducts. Between the inner and outer circles 
there are numerous other less regularly disposed ducts. The pre- 
ceding facts are shown in fig. 43, though not so clearly as I should 
have liked. Resin ducts occur in the cotyledons also. In the base 
they accompany the vascular bundles and are just below the 
epidermis of the outer face of the cotyledon, but not on the inner 
side of the bundles. Farther out toward the tips the outer ring 
extends completely around beneath the epidermis, in much the 
Same way as in the hypocotyl. Resin ducts do not appear to 
extend upward in the embryonic mass from which the final embryo 
is differentiated beyond the dark line shown in the upper part 
of fig. 42. 
In the subsequent growth of the embryo the hypocotyl changes 
very little, while the cotyledons elongate enormously. At the 
time the seeds drop from the cone axis (late November to January), 
the embryo is about 3 cm. long, of which the hypocotyl forms about 
5-6 mm. At this time the embryo is quite straight and extends 
to within about 1 cm. of the tip of the endosperm. The hypocotyl 
is crowded closely into the apex of the seed. 
