PROPAGATION OF PLANTS. 141 
The air has not access to them, and therefore, from the want 
_ of this important stimulus, they remain torpid. Hence it is 
_ that earth newly dug up frequently becomes covered with 
weeds, the seeds of which soon germinate when exposed to 
he air. 
558. Placing seeds at a certain depth in the earth, ex- 
ludes them from the access of light, which is so injurious to 
germination ; insures a supply of moisture, which would not. 
remain with them were they placed at the surface ; protects 
them from the wind, and from the attacks of animals; and 
enables the roots to take a firm footing in the soil. 
959. When germination has commenced, the seed be- 
comes soft, and swells ; carbonic acid is disengaged, and oxy- 
gen absorbed; the particles of the episperm lose their co- 
hesion, and it is burst to make way for the elongation of the 
mbryo ; the radicle elongates and descends, often attaining 
‘ considerable length before the gemmule has made any pro- 
gress, and soon exercising its function of absorbing food ; the 
albumen is gradually absorbed, and disappears: the cotyle- 
dons expand and become seminal leaves, which afford nou- 
rishment to the young plant, in the first stages of its existence, 
y elaborating the sap, and wither when the proper leaves of 
the plant have unfolded—or remain under the surface, are 
gradually absorbed, and disappear : the gemmule or first bud 
gradually unfolds, and enlarges; the primordial leaves and 
stem appear ; and we now have a young plant—a living being, 
able to provide its own sustenance; to elaborate that susten- ie 
ance, and to apply it to its increase, and to the formation of — 
those wonderful organs by which it is enabled to perpetuate 
is species, Soe eae 
_ 560. In the operation of malting, the object is to convert — 
‘the farina or hordein of the albumen into sugar. For this 
‘Purpose the seed is made to germinate: and this process i 
stopped at that point at which it has been found there is the 
quantity of saccharine matter in the seed. We 
ion allowed to proceed farther, the saccharine 
