On the Food of Plants. 327 
antiguity, either when the hill country, like the low lands, 
formed part of an extensive forest; or more probably when 
these extensive downs were subject to the plough. 
Being soliciteus te know whether these seeds were ante- 
diluyian, I took earth from different depths, and soon got 
below the stratum in which these seeds are found. 
The necessity of air for the vegetation of seeds will ac- 
count for effects which in agriculture are too frequently ob- 
served. 
If soon after wheat or barley has been sown on what is 
called arunning sand there falls a dashing rain, the sand 
ruus together, that is, it forms a crust, which in a great 
measure is impervious to air, and scarcely a grain of corn 
will grow ; or if on clay land, during a time of drought, a 
garden plot is watered, and left exposed to the scorching 
beams of a meridian sun, the ground will bake, that is, the 
surface will be hardened, and being thus rendered imper- 
vious to. air, vegetation ceases. But if the surface has been 
previously covered with fern leaves, as practised by skilful 
and attentive gardeners, no such effect will be produced. 
The plot may be watered, and vegetation will be rapid. 
The admission of air, and its vast importance to the 
growth of plants, will account for the good effect produced 
by harrowing our wheat crops in spring, as lately intro- 
duced, and now universally adopted by our best farmers. 
The good effect produced is made apparent by the luxuriant 
growth of pease, beans, turnips, and cabbages, after they 
have been hoed; and is at present so well understood, that 
many agricuiturists hoe their turnips twice, and their beans 
four times, not merely with a view to the destruction of 
weeds, but because they observe the benefit arising to their 
crops by the free admission of air into the earth, The pal- 
pable advantage of this practice has led many farmers to 
consider the principles on which the practice has been 
founded, and to try by experiments how far it can be 
pushed. 
In this pursuit, and satisfied of the benefits to be derived 
from loosening the surface of the ground contiguous to his 
crops, the Rev. Mr. Close has given up the broad-cast hus- 
X4 bandry, 
