Tlie Seed and its Germination. 
493 
with no further appliances than a small knife and a needle or 
two. The dissection is very simple, and may be effected with- 
out the assistance of a microscope. To 
display the parts of the common bean 
it is advisable to soak one in water for 
twenty-four hours, when it will be 
found to have swollen up slightly, and 
to be easily manipulated. At one end 
of it will be noticed a black patch (the 
hilum) which marks the place at which it 
was attached to the pod. If it be carefully 
pressed a minute drop of water will be 
squeezed out of it, close to the part of 
this patch which is next to the broad 
end of the bean. This indicates a 
small opening in the testa or skin, 
through which when the seed was 
young the tube or outgrowth from the 
pollen grain entered it to fertilise the 
germ cell. This opening is technically 
known as the microyyle. If now the 
skin be carefully slit open and peeled 
off, the whole of its cavity will be found 
to be occupied by the embryo. The 
great mass of this consists of two large 
fleshy lobes which are pressed face to 
face, but do not adhere together. These 
are the cotyledons (fig. 1, c). Joining 
these cotyledons together will be found 
the rest of the embryo, which consists 
of an axis, showing at the one end a root 
or radicle (fig. 1, r) lying outside the 
cotyledons, and pointing towards the 
micropyle, and at the other the rudi- 
mentary stem (fig. 1, p) which is folded 
inwards, and so lies hidden by the 
cotyledons. This can only be seen 
removed. 
Another seed which should be dissected is that of the buck- 
wheat. This is a triangular seed with sharp angles. The so- 
called " seed," as we find it, is really the fruit, which is hard 
and dry. The black outer skin is the wall of the fruit or the 
pericarp. With a little care this can be removed by a sharp 
knife or a stout needle — more easily if it has been soaked for 
a time in water. Inside is found the seed with a. thinner, more. 
Fig. 6. — Section of Grain of 
Barley. 
i, palea ; i, pericarp of grain ; c, 
endosperm ; d, scutellum ; e, epithe- 
lium of scutellum ; /, embryo. 
when one cotyledon is 
