chap, vii.] WALL-FRUIT TREES. 
207 
they should be removed, and trees of quite a 
different kind, such as pears for example, 
planted instead of them in the same soil. 
When the borders cannot be spared to be left 
entirely bare, a light crop, such as of spinach, 
lettuces, mustard and cress, or parsley, should 
be sown on them, and the remains of this 
crop, when done with, should be raked off; 
but fruit borders should never on any account 
be touched with a spade, and even a fork 
should be used very seldom and very spar¬ 
ingly ; never, indeed, unless the ground has 
become too hard and compact to admit the 
rain, the sun, and the air. It must never be 
forgotten, that unless the spongioles of the 
roots are permitted to imbibe the carbonic 
acid gas always floating in the atmosphere, 
with the moisture they take up, the sap of 
the tree will never be rich enough to produce 
fruit. The fruit and seeds of every plant are 
in fact concentrations of carbon, precipitated 
by the action of light; and where any plant 
is deficient in carbon, or deprived of light, it 
cannot produce much fruit. The culture of 
the nectarine is exactly the same as that of 
the peach* In both, when the season is cold 
