274 Linnean Society. 
embryo. A little later, the conical, originally rectilinear apex of the 
embryo has become. somewhat oblique, and a depressed areola makes 
its appearance on one side of the head of the embryo. In the next 
stage the conical and rather oblique apex of the embryo protrudes 
through the apex of the nucleus, and its base has become enlarged 
and roundish. The conical apex and head of the embryo become 
still further protruded, and from the margin of the depressed areola 
are produced minute, oblong, obtuse, cellular bodies, which are the 
rudiments of the outer processes of the plumula. These gradually 
enlarge, and others are developed within them from the centre or 
disc of the areola; and at the same time the conical apex of the 
embryo becomes more and more oblique. At this period the chief 
bulk and enclosed part of the embryo occupies about the upper 
two-thirds of the excavation of the nucleus, but does not as yet ex- 
tend into its lower globular portion; and the enclosed part is firmly 
embraced by the neck of the nucleus, the tissue of which has become 
more and more callous or indurated. Still later the testa becomes 
more enlarged and cellular, and its foramen more indistinct; the 
nucleus is denser and more cellular, and the embryo extends down- 
wards into the globular portion of its cavity, displacing the sacci- 
form cellular tissue with which it was previously filled. The ex- 
serted portion of the embryo now ceases to elongate, but increases 
greatly in a transverse direction; the area on which the processes 
of the plumula are developed is much enlarged, they become more 
numerous and elongate rapidly, and, as the testa does not increase 
with equal rapidity, their apices become recurved. The radicle in- 
creases much less rapidly, but becomes gradually more and more ob- 
lique, and is soon imbedded in the lax testa, which it finally perfo- 
rates. 
The fully-developed seed is oblong, somewhat compressed, de- 
pressed on its inner, convex on its outer surface, and constricted 
towards the hilum, where it is of a brownish tint and hard to the 
touch. The testa closely embraces the plumula; it is cellular to- 
wards its base and where it surrounds the dense internal globular 
body, membranous throughout the rest of its extent, and so thin 
that the processes of the plumula are visible through it and give it a 
greenish tint. ‘The descending portion of the embryo, which con- 
stitutes the cotyledon, is clavate and nearly enclosed within the dense 
indurated nucleus, the enclosed part separating with the nucleus with 
great readiness, and about the time of the dehiscence of the fruit 
spontaneously. The exserted portion of the embryo consists ex- 
clusively of the base of the cotyledon, of a fleshy plano-convex body, ~ 
the plane surface of which is depressed towards the centre, where 
the cotyledon is attached, and gives origin on one side to the conical 
and acute radicle, which is always directed away from the placenta. 
The circumference of the convex surface is entirely occupied by the 
processes which constitute the plumula, and the outermost of which 
are about an inch in length, These processes are furnished with 
vessels, but their chief bulk is cellular, and they are (with the ex- 
ception perhaps of the outermost) furnished with stomata. After 
