90 
SEED. 
a. The seed consists of the nucleus^ or kernel, and its %nteg'w» 
ment^ or covering. The eye of the seed^ or hihim^ is the scar 
formed by the separation oii}iQfunicle. This connecting mem- 
brane is usually very short ; but in the magnolia^ and some 
other plants, it is several inches in length. When the seed 
is fully ripe, its connection with the pericarp ceases by the 
withering and separation of the funicle, leaving upon the outer 
surface of the seed the mark of its insertion. 
This scar, or eye, is very conspicuous in the bean, which also exhibits 
the pore { foramen) through which the nourishment was conveyed to the 
internal parts of the seed. That part of the seed which contains the eye 
is called the base ; the part opposite is called the apex. Fig. 115 rep- 
resents the garden bean ; it is an oblong, tunicated seed, with two thick 
cotyledons ; at a may be seen the hilum, or eye. 
The integument is called the spermoderm (from sperma^ seed, 
and derma^ skin) ; it consists of three coats, the external shln^ 
called the testa or cuticle^ the cellular tissue, called m^sosperm^ 
and the internal skin, or endosperm. The outer coat of the 
seed is important, as the kernel, originally a fluid, could not 
be formed without its presence. 
The Kernel.^ or nucleus, includes all that is contained within 
the sjpermoderm / the kernel consists of the alburiien., cotyledon^ 
and einbryo. The Albumen is the substance which, in many 
seeds, is intermediate between the outer integument and the 
embryo. It is thought to afford support to the germinating 
embryo plant, as does the white of an egg to the embryo bird. 
Both in respect to hardness and color, the albumen in many seeds greatly resem- 
bles the white of a boiled egg. It is farinaceouH, or mealy, consisli/ig of cells filled 
with starch, as in buckwlieat, and horn-like in coffee. The seeds of the pea and of 
the cruciform plants are destitute of albumen. In some cases the embryo is in- 
closed within a sac, called vitellus, corresponding to the yolk of an egg ; it is one of 
the proper coats of the nucleus which has not been absorbed or converted into 
albumen during the development of the seed. It is not considered an essential 
part of the seed, because it is sometimes wanting ; but when present, it supports 
and defends the embryo while imprisoned in the seed, and serves for nutriment 
when it begins to germinate. Albumen makes up the chief part of some seeds, as 
the grasses, corn, tfec. ; in the nutmeg, which has very small cotyledons, it is remark- 
able for its variegated appearance and aromatic quality. It chiefly abounds in 
plants which are furnished with but one cotyledon. 
Cotyledons (from hotule., a cavity) are the thick lobes of seeds. 
They are the first visible leaves ; often fleshy and spongy, of a 
succulent and nourishing substance, which serves for the food 
of the embryo at the moment of its germinating. 
Nature seems to have provided the cotyledons to nourish tlie plant 
in its tender infancy. After seeing their young charge sufficiently vig- 
orous to sustain life without their assistance, the cotyledons in most 
plants wither and die. Fig. 116 represents the cotyledons of the bean, 
as divested of the outer covering ; a a represent the two cotyledons ; 
b and c, the embryo ; d shows the petioles or stems of the cotyle- 
dons. 
a. Parts of the seed— Eye -Integument— The kernel, its parts— Albumen— Cotyledons 
