and spongy, and, as it always prefers a dry
calcareous, even stony, soil, the northern cultivators find that by
selecting such localities the tissues of the plant take up so little
water that the frost does not injure them.

In a northern climate the length of the days in summer, and the natural
dryness of the air, compensate in some measure the reduction of
temperature, and mature the plant only to the extent sufficient for the
purpose for which it is grown. Perhaps the suspension of vital action
during winter, which must be more complete in northern latitudes, as our
frosts are more severe, tends to preserve certain plants, native of the
south, for it is observed that all plants are more sensitive to cold
when vegetation is active than when it is at rest. The vine is an
instance of this. On the other hand, when the plant is cultivated
further south than its natural boundary, the same causes seem to exert
their influence, but in the reverse sense. Lavender is cultivated on the
mountains of Yemen, in Arabia; the humidity, increasing inversely to the
latitude, compensates the exhaling force of the sun's rays, and the
elevation of the locality the effects of the heat.

Thus is confirmed, both in north and south, the law of vegetable
physiology observed by De Candolle, in the temperate climates of France,
and published in his "Essai de Geographie Botanique," that "plants can
best resist the effects of cold in a dry atmosphere, and the effects of
heat in a humid atmosphere." A mild, damp winter, like the one of
1889-1890, does more harm than a hard, seasonable frost, as the plants
are apt to make green shoots prematurely, and the late frosts nip off
these tender portions, each of which would otherwise have produced a
flower spike.

The very severe winter of 1890-1891 did not kill so many plants as the
one of 1889-1890. The stems and branches of lavender being ligneous and
strong are able to resist the force of the wind, and the plant thrives
best in a perfectly open locality, where the air circulates freely; the
oil and resin which it contains in abundance enable it to resist the
parching action of the wind and sun. Thus, on the most arid and sterile
ground on the mountain sides in the south, and especially in Spain,
plants of this genus flourish with more vigor in the season when most
other vegetation is scorched up by the ardent rays of the sun, and the
_Lavandula vera_ seems to have a predilection for such spots.

C