46 
SOWING SEEDS. 
j^CHAP. III. 
slugs and all kinds of insects, and to become 
rotten by damp, or withered by heat. It is 
also very possible to bury a seed so deeply 
as to prevent it from vegetating at all. The 
ground has more of both warmth and moisture 
near the surface than at a great depth, as it 
is warmed by the rays of the sun, and 
moistened by the rain; but besides this, seeds 
will not vegetate, even when they are amply 
supplied with heat and moisture, if they are 
excluded from the influence of the air. Every 
ripe seed in a dry state is a concentration of 
carbon, which, when dissolved by moisture, 
and its particles set in motion by heat, is 
in a fit state to combine with the oxygen 
in the atmosphere, and thus to form the car¬ 
bonic acid gas which is the nourishment of 
the expanding plant. For this reason, seeds, 
and newly sprung-up plants do not want to 
be supplied with manure, and air is much 
more essential to them: they have enough 
carbon in their cotyledons or seed-leaves, 
and they only want oxygen to combine with 
it, to enable them to develope their other 
leaves; and this is the reason why young 
plants, raised on a hotbed, are always given 
