HOW PLANTS GROW FROM THE SEED. 
15 
embryo imbibes and feeds on as it sprouts. That the meal or starch of the grain 
is actually changed into sugar at this time is clearly shown by malting, which is 
merely causing heaps of grain to sprout a little, and then destroying the life of 
the embryo by dry heat ; when the grain (now malt) is found to be sweet, and 
to contain much sugar. 
36. The nourishment which the mother-plant provides in the seed is not always 
stored up outside of the embryo. In many cases it is deposited in the embryo 
itself, most commonly in the seed-leaves. Then the seed consists of nothing but 
the embryo within its coats. Maple-seeds are of this sort. Fig. 24 represents a 
seed of Red Maple in the lower part of the winged seed- 
vessel, which is cut away so as to show it in its place. Fig. 
25 is the seed a little magnified, and with the coats cut away, 
bringing to view its embryo coiled up within and filling the 
seed completely. Fig. 26 is the embryo taken out, and a 
little unfolded ; below is the radicle or stemlet ; above are the 
two seed-leaves partly crumpled together. 
Fig. 27 is the embryo when it has straight- 
ened itself out, thrown off the seed-coats, 
and begun to grow. Here the seed-leaves 
are rather thick when they first unfold ; this 
is on account of the nourishing matter which, 
was contained in their fabric, and which is, 
used mainly for the earliest growth of the 
radicle or stemlet, and for the root formed 
at its lower end, as we see in the next fig- 
ure (Fig. 28 : a, the radicle or stemlet of the embryo ; 5, 5, the two seed-leaves ; 
c , the root). By this time the little stock of nourishment is exhausted. But the 
plant, having already a root in the soil and a pair of leaves in the air, is able to 
shift for itself, to take in air, water, &c., and by the aid of sunshine on its foliage 
to make the nourishment for its future growth. In a week or two it will have 
made enough to enable the next step to be taken. Then a little bud appears at 
the upper end of the stemlet, between the two seed-leaves, and soon it shows 
the rudiments of a new pair of leaves (Fig. 28, d) ; a new joint of stem forms to 
support them (Fig. 29) ; this lengthens just as the stemlet of the embryo did, and 
so the plantlet gets a second pair of leaves, raised on a second joint of stem. 
