6g 6 
Hill and de Fraine* — On the 
has two cotyledons, each of which is traversed by two vascular strands, and 
Van Tieghem 2 indicates that the primary root of Phyllocladus is diarch in 
structure. 
CUPRESSINEAE. 
Juniperus virginiana , Linn. The morphology of the seedling in 
this, and also in the other species examined, calls for no special comment. 
The epigeal cotyledons are two in number, ligulate in shape, and inserted 
on the slender hypocotyl, which is continued downwards into the primary 
root. 
Structure of the Cotyledon . Each cotyledon has a single vascular 
strand, which is collateral throughout its entire length. The bundle is 
somewhat tangentially elongated, and transfusion tracheides are fairly 
common, although they are not so abundant in this species as in some 
others, e. g. J. Cedrus (Fig. 8, Plate XXXV). A few xylem elements may 
occasionally be seen on the ventral side of the protoxylem, hence the 
cotyledonary bundles are slightly mesarch in structure (cf. Fig. 8, 
Plate XXXV). 
The remaining structural features are identical with those of the 
seed-leaves of Tax us and Cephalotaxus , and therefore require no further 
comment. It may be remarked that no resin canals have been seen in 
the cotyledons of this and the preceding plants ; they are, however, 
prominent features in the first foliage leaves of Juniper us, each having 
one duct situated immediately below the dorsal ridge (see Diag. 3, 
Fig. 1). 
Transition . The seed -leaf-traces enter the hypocotyledonary axis as 
collateral structures, and travel obliquely downwards towards the central 
cylinder (Fig. 9, Plate XXXV). During this passage, which may take place 
somewhat quickly, the phloem of each bundle bifurcates, leaving the xylem 
exposed on the dorsal side, and, at the same time, there is a slight rotation 
of the contiguous half-bundles, which brings the metaxylem elements into 
a position somewhat more internal than the protoxylem. As a result 
of this, when the central cylinder is just about reached, each cotyledon- 
trace has a central mass of xylem, bounded on each side by two separate 
groups of phloem elements, which lie in a position at right angles to the 
plane of insertion of the seed-leaves (Diag. 3, Fig. 3). 
The protoxylem is almost in an exarch position, but not quite ; 
it is still covered externally by a few metaxylem elements. In other 
words, the protoxylem, for a time, is in the mesarch position (Diag. 3, 
Figs. 4 and 5, and Figs. 9 and 10, Plate XXXV). The protoxylem finally 
becomes exarch by its own somewhat indefinite efforts, aided by the 
inward movement of the metaxylem. Concurrently, the opposing masses 
1 Van Tieghem, loc. cit. 
