r germ to the yolk. So
the matter around or by the side of the embryo was called the _Albumen_,
i. e. the white of the seed. The analogy is not very good; and to avoid
ambiguity some botanists call it the ENDOSPERM. As that means in English
merely the inwards of a seed, the new name is little better than the old
one; and, since we do not change names in botany except when it cannot
be avoided, this name of _albumen_ is generally kept up. A seed with
such a deposit is _albuminous_, one with none is _exalbuminous_.

32. The ALBUMEN forms the main bulk of the seed in wheat, maize, rice,
buckwheat, and the like. It is the floury part of the seed. Also of the
cocoa-nut, of coffee (where it is dense and hard), etc.; while in peas,
beans, almonds, and in most edible nuts, the store of food, although
essentially the same in nature and in use, is in the embryo itself, and
therefore is not counted as anything to be separately named. In both
forms this concentrated food for the germinating plant is food also for
man and for animals.

[Illustration: Fig. 40. Seed of Morning Glory divided, moderately
magnified; shows a longitudinal section through the centre of the embryo
as it lies crumpled in the albumen. 41. Embryo taken out whole and
unfolded; the broad and very thin cotyledons notched at summit; the
caulicle below. 42. Early state of germination. 43. Same, more advanced;
caulicle or primary stem, cotyledons or seed-leaves, and below, the
root, well developed.]

33. For an albuminous seed with a well-developed embryo, the common
Morning Glory (Ipomoea purpurea, Fig. 40-43) is a convenient example,
being easy and prompt to grow, and having all the parts well apparent.
The seeds (duly soaked for examination) and the germination should be
compared with those of Sugar and Red Maple (19-21). The only essential
difference is that here the embryo is surrounded by and crumpled up in
the albumen. This substance, which is pulpy or mucilaginous in fresh and
young seeds, hardens as the seed ripens, but becomes again pulpy in
germination; and, as it liquefies, the thin cotyledons absorb it by
their whole surface. It supplements the nutritive matter contained in
the embryo. Both together form no large store, but sufficient for
establishing the seedling, with tiny root, stem, and pair of leaves for
initiating its independent growth; which in due time proceeds as in Fig.
44, 45.

[Illustration: Fig. 44. Seedling of Morning Glory more advanc