to) ELEMENTARY BOTANY 
Whilst developing, the embryo feeds on the endosperm. 
Sometimes all this food material is absorbed during the ripening 

Fic. 70. — POoLien 
GRAIN ON STIGMA 
PUTTING OUT ‘TUBE 
TO OVULE (semi 
diagrammatic). 
p.t, pollen tube; es, 
embryo-sac ; 7, nu- 
cellus ; int, integu- 
ments; k, lower 
part of calyx cup. 
of the seed, but sometimes not until ger- 
mination. In the first case the seed is 
sald to be exalbuminous, that is, 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 
denotes exactly the same part of the 
seed as that designated “albumen.” The 
bean seed, described in Chapter I., is 
exalbuminous, for it consists simply of 
testa and embryo. On the other hand, 
the maize seed is albuminous, for it 
contains in addition to testa and 
embryo, the endosperm, whicl occupies the greater part of 
the seed. 
TABLE SHOWING FORMATION OF SEED FROM 
OVU LE. 
OVULE. SEED. 
I. Stalk. I. Stalk of attachment. 
2. Usually two integuments. 2. The testa. 
3. Micropyle. 3. Hole in testa, also called 
micropyle. 
4. MacrosporeorEmbryo-sac. 4. Embryo + endosperm, 
5. Oosphere. 
which may, or may not, 
be absorbed by embryo. 
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 
