Seedling Structure of Gymnosperms. II. 199 
Attention also may be drawn to another feature. In Series A there 
were eleven seed-leaves and the same number of leaves in the first foliage 
whorl of the plumule. Of these foliage leaves one was much larger than the 
rest, with a more massive vascular bundle which showed a greater vascular 
differentiation. Further, It fused on to the cotyledonary tube before any of 
Its fellows, and its bundle took up a position slightly more external than the 
other strands ; it also retained its vascular differentiation for a longer period 
than the other bundles of the first foliage whorl. The probable significance 
of this will be dealt with below (see Finns Pinea, Series C). 
PlNUS. 
The cotyledons vary in number from three to about twelve, and their 
structure does not differ, excepting in a few features, in certain species, from 
the foregoing plants. Resin ducts are generally present, the only two 
species in which they have not been observed being P. halepensis and 
P. Coulteri. In P. Pinea, P. Gerardiana, and P. canariensis each cotyledon 
has two resin ducts situated in the dorsal corners of the leaf ; in P. australis , 
P. insignis, P. contort a y P. con tort a var. Murray ana, P. montana var. gallica y 
and P. sylvestris each seed-leaf has one resin duct situated immediately on 
the dorsal side of the vascular bundle or else in between the two halves 
of the divided trace (see Diagram 4, Fig. 1). The general rule is for each 
cotyledon to have a single vascular strand ; there are, however, exceptions, 
thus in P. montana var. galiica and P. contorta var. Murrayana y some of the 
seed-leaves have two separate vascular strands. 
The cotyledonary bundles may show no rearrangement at all in the 
seed-leaf, as in P. Pinea, P. Thunhergii, P. Gerardiana, and P. halepensis ; 
or they may undergo bifurcation of the phloem and rotation of the xylem 
before entry into the hypocotyledonary axis, as in P. Coulteri, P. canari- 
ensis, P. australis y P. insignis , P. contorta, P. contorta var. Murrayana, 
P. montana var. galiica, and P. sylvestris. 
The bundles of P. Pinea and P. Gerardiana, very occasionally show 
one or two metaxylem elements on the ventral side of the protoxylem, the 
strands thus being very slightly mesarch. Fibrous elements on the dorsal 
side of the soft bast are generally present ; and, finally, the majority of the 
species examined exhibit in varying degrees a lateral fusion of the cotyle- 
dons towards their bases ; the best cotyledonary tubes were seen in 
P. Pinea and P. canariensis, in the other species the tube was either very 
short or incomplete. 
Pinus Pinea. Excellent figures representing different stages in the 
germination of this plant are given in Sachs’s Text-book. 1 
1 Sachs : Text-book, Oxford, 1882, p. 508. 
