Seedling Structure of Gymnosperms . /. 707 
this plant, each seed-leaf has three resin ducts situated just below the 
epidermis, one at each end of the leaf, and the other immediately above 
and dorsal to the vascular bundle. 
The changes leading to the root-structure are initiated during the 
inward passage of the traces from the cotyledons, and resemble those 
obtaining in Juniperus virginianum . 
Fig. 12, PI. XXXV, represents a rather curious feature in the seed-leaf 
bundles in one plant of this species. Each strand entered the axis without 
any signs of bifurcation of the phloem or rearrangement of the xylem. 
A cambium extended first on one side of each bundle and then on the 
opposite side, the activity of this meristem, in each cotyledon-trace, gave 
rise to an almost concentric vascular strand. 
A more remarkable abnormality occurred in another individual. 
After the transition had been practically effected, meristems arose towards 
the inner sides of each xylem mass (Diag. 8, Fig. 1). These cambiums 
effected a junction so that a semi-circular strand occurred on the inner side 
Diagram 8. Sequoia sempervirens . Black lines represent cambium, the other markings, as 
before. 
of each bundle of wood-elements (Diag. 8, Fig. 2). The opposing groups 
of phloem then underwent a gradual centripetal displacement, met in the 
centre of the axis, and gave rise to an arrangement indicated in the third 
figure of Diag. 8. The cambium formed a few phloem elements and 
parenchyma cells, but not in a quantity sufficient to cause crushing (Fig. 33; 
Plate XXXV). On tracing the tissues still further downwards, the phloem 
bridge thinned out, and finally broke ; thus the normal disposition of tissues 
was reattained (Diag. 8, Figs. 4 and 5). 
Sequoia gigantea , Lindl. & Gord. The number of seed-leaves is 
usually three or four ; structurally they resemble S. sempervirens , excepting 
that only one resin duct is present in each, that on the dorsal side of the 
vascular strand ; also, the transfusion tissue is somewhat more abundant 
than in X. sempervirens. 
Taking first a Dicotyledonous specimen, it was found that the 
transition was identical with what obtains in Widdringtonia Whytei, 
the main feature being that bifurcation of the phloem and rotation cif 
the xylem to assume the exarch position, takes place while the bundles 
3 B 2 
