636 
PHANEROGAMS. 
between them is pushed out (Fig. 438), and now grows upright so that the seed 
and cotyledons together have the appearance of being a lateral appendage of the 
axis of the embryo. But usually the cotyledons are destined for further develop- 
ment, especially when they are thin, and form the first foliage-leaves of the plant. 
In order to liberate them and the plumule which lies between them from the seed, 
the hypocotyledonary portion of the axis increases considerably in length, making 
Fig. 437. — Longitudinal section of the axis of the FiG. 438. — Qtcerctes Rohur ; I longitudinal section of the embryo (rnag- 
enibryo in the ripe seed of Phaseohis muUiflorus , nified) after removal of the anterior half of both cotyledons c, c; the 
parallel to the cotyledons (X about 30) ; ss apex of the hypocotyledonary portion of the axis he, the primary root w, and plumule 
stem, 7VS of the root, ct cushion at the insertion of d are concealed between the lower portion of the thick cotyledons ; st 
the cotyledons, z'the first internode, /(!> the petioles of petiole of the cotyledons ; // seed at the time when germination is com- 
the first foliage leaves, v,-u,ft.\ie procambium of the mencing (natural size), the pericarp and one cotyledon have been removed, 
fibro-vascular bundles. the hypocotyledonary portion of the axis and the radicle have elongated ; 
/// further stage of germination, the plumule having emerged from the 
testa sh and pericarp s by the elongation of the petiole of the cotyledons 
St, TV primary root, w' secondary roots. 
first of all a curve which is convex on the upper side (Fig. 435), because the coty- 
ledons still remain in the seed while the lower end of the stem is attached by the 
root to the ground. Ultimately, by a final lengthening of the hypocotyledonary 
portion, the upper part of the axis together with the cotyledons is drawn out of 
the seed in a pendent position. The axis now straightens as it continues to grow, 
and the cotyledons expand in the air, the plumule developing more completely and 
