58 ELEMENTARY BOTANY 
Whilst developing, the embryo feeds on the endosperm. 
Sometimes all this food material is absorbed during the ripening 
: of the seed, but sometimes not until ger- 
mination. In the first case the seed is 
sald to be exalbummnous, that 1s, without 
albumen ; in the latter it is albuminous, 
This term “albumen” denotes the 
chemical composition of which the endo- 
sperm or food material is composed and 
is still retained in botany, because it is 
usual and convenient to speak of seeds 
as albuminous or exalbuminous. The 
: term “endosperm” is a better one, and 
ees e ee denotes exactly the same part of the 
_Purtinc our Tune seed as that designated “albumen.” The 
a Ovure (sem ean seed, described in Chapter I. is 
lagrammatic). 
p.t, pollen tube; es, exalbuminous, for it consists simply of 
embryo-sac; NU testa, and embryo. On the other hand, 
cellus ; ant, integu- : 
ments; k, lower the maize seed is albuminous, for it 
pare eee eur centains. tn addition to testa and 
embryo, the endosperm, which ee the greater part of 
the seed. 

TABLE SHOWING FORMATION OF SEED FROM 
OVULE. 
OVULE. “SEED. 
LeStank I. Stalk of attachment. 
2. Usually two integuments. 2. The testa. 
3. Micropyle. ~ 8. Hole in testa, also called 
micropyle. 
4. MacrosporeorEmbryo-sac. 4 Embryo + endosperm, 
, which may, or may not, 
be absorbed byembryo. 
5. Oosphere. | 5. Embryo. 
A seed is therefore a macrosporangium, enclosing a young 
plant, the embryo, which is set free from the parent plant 
in order to produce a new plant. Only Flowering Plants form 
