The Cultivation of Vegetables 85 
the nitrogen gas of the atmosphere, as one of the most 
valuable plant foods, viz. the nitrates. If the root of a 
pea or other leguminous plant be examined, little nodules 
or swellings will be found all over it. This is not a disease, 
as was at first supposed, but these little nodules, when cut 
through with a razor and examined under the microscope, 
; are found to be full of tiny moving living things. These 
: are bacteria, the most minute organisms imaginable. They 
extract the nitrogen gas from the atmosphere and change 
it into nitrates in their bodies, after which it is absorbed 
by the pea plant as its food. Nitrate is one of the 
principal ingredients in farmyard manure. Peas do not 
require a large supply of this manure. Soil which has 
been well manured the previous year will generally be 
found to be rich enough for them, but the soil must be 
thoroughly dug or trenched. 
The first sowing may be made as soon as the soil is in 
order in March. The line having been properly set, drills 
about 3 in. deep should be drawn with the flat of the hoe, 
the handle of the hoe being held fairly high, cutting the 
soil rather than drawing it, thus allowing it to fall out to 
either side of the drill. The seed should be sown thinly, 
allowing at least 2 in. in all directions between the seeds. 
They should then be covered up with the rake, pushing 
half the soil in from one side, and pulling the other half 
in from the other, leaving a very slight ridge along the 
centre of the row. 
It is not necessary to tread the soil on the top of the 
seeds in this case, as they are deep enough in the soil to 
ensure them being kept uniformly moist until germination 
has taken place. As birds are very fond of the young 
