5o8 
PHANEROGAMS, 
contained in the seed j in most Conifers, on the contrary, this portion becomes 
greatly elongated, making a sharp bend in an upward direction, pierces the soil, 
and draws the cotyledons with it. As soon as these are exposed to light, the 
hypocotyledonary portion straightens itself, the whorl of cotyledons expand, and, 
having become green while still underground, act as the first foliage-leaves of 
Fig. ^iß.—Pinus Pinea; I longitudinal section tbroup^h the middle of the seed, ^ the micropylar end ; // commencement 
of germination, emergence of the root ; /// completion of germination, after the endosperm has been absorbed (the seed 
lay at too small a distance below the surface, and was therefore raised up by the cotyledons when the stem began to grow) ; 
A shows the ruptured testa j, B the endosperm e, one half of the testa having been removed, C longitudinal section of the 
endosperm and embryo, D transverse section at the commencement of germination; c the cotyledons, iv the primary root, 
X the embryo-sac pushed out by it (ruptured in B), he hypocotyledonary portion of the axis, iv' secondary roots, r red mem- 
brane within the hard testa. 
the seedling, the apex of its axis having in the meantime formed a bud with 
new leaves (Fig. 346). 
Mode of Growth and External Differentiation. The terminal bud of the stem 
of the seedling grows more rapidly, though frequently interrupted, than the lateral 
shoots which arise subsequently. The primary stem is thus a direct prolongation of 
the axis of the embryo; it never ends in a flower, but grows indefinitely at the 
