EEAT. 
brids may be readily cross-bred with 
each other, the number of kinds 
that may be raised defies all calcu- 
lation. The Heart’s-ease must be 
grown in very rich soil, composed, 
if in pots or boxes, of four parts of 
rich loam, one of sand, and one of 
decayed leaves, or roiten dung ; and 
if in the open ground, of rich loam 
highly manured. It is propagated 
by seeds, or division of the root. 
‘The seeds should be sown as soon | 
as they are ripe in a bed, where the 
young plants should remain till they 
flower, when the best should be 
taken up and replanted in another | 
bed, or in well-drained pots or boxes, 
for flowering. The plants will re- 
quire constant watering during the 
hot weather ; but they are very apt 
to damp off if the soil in which 
they grow has not been well drained. 
The best varieties are propagated 
by cuttings taken off from the points 
of the sheots, in the spring, cutting 
them clean across immediately be- 
low a joint. The cuttings should 
be struck in pure white sand, and 
covered with a bell-glass; they 
should not be watered when put in, 
and they sheuld be shaded for seve- 
ral days. MHeait’s-eases are also 
propagated by layers, pegged down 
at a joint, but not slit, on account 
of their tendency to damp off. 
Heart is concentrated or produced 
in gardens in a variety of ways: by 
shelter from winds, which prevents 
the natural heat of the plants from | 
being carried of by currents of air | 
passing over them ; by exposure to 
the sun, which concentrates its 
rays ; by covering a surface of soil 
or the roots and stems of plants with 
a non-conducting material, such as 
straw, litter, leaves, &c., which pre- 
vents its radiation; by fermenting 
substances, such as_ stable-dung, 
litter, leaves, tan, &c., which pro- 
duce heat by their decomposition ; 
and by the consumption of fuel, 
‘from which the heated air generated 
243 
HEDERA. 
is conducted in flues, or by means 
of pipes of hot water orsteam. Hot- 
beds are generally heated by a bed 
of horse-dung, or other fermenting 
material; and brick-built pits, or 
houses with glass roofs, are heated 
by furnaces and flues, or furnaces, 
boilers, and pipes of hot water or 
steam. Stable-dung and hot-water 
| pipes are the two best modes of heat- 
ing pits and glass-roofed houses. 
Heat when produced is retained by 
coverings which admit the light, 
such as glass sashes, or in some 
cases frames covered with oil-paper, 
or with very thin canvass or gauze 
Heats.—See Ert'ca. 
HEArTH-MOULD is very frequently 
confounded with peat-bog, by ama- 
teur gardeners ; but the fact is, they 
are materially different. Black peat, 
which consists of vegetable fibre, 
prevented from decomposing by a 
| superabundance of water, is unfit 
for the growth of plants when in a 
pure state ; but heath-mould, or peat 
nixed with sand, is admirably adapt- 
ed for the growth of all Australian 
and American hair-rooted plants, as 
the mixture of sand with the peat 
prevents its retention of water; it 
is only the retention of water that 
prevents the decomposition of the 
vegetable matter it contains.—See 
PEAT-BOG. 
Hr’persa.—Aralidcee.—The Ivy. 
This well-known plant is what bot- 
anists call a rooting climber; that 
is to say, its stems climb up and 
wind themselves round trees, or any 
other suitable object which presents 
a sufficiently rough surface for their 
roots to take hold of; as, unless this 
is the case, the Ivy, whenever it is 
rendered heavy by rain or snow, 
falls down. Whenever, therefore, 
Ivy is wanted to cover smooth, 
newly-plastered walls, trellis-work 
should be fixed against.them, to 
which the Ivy should be nailed like 
any other plant. The Ivy is re- 
markable for undergoing a complete 
