in the northern countries like the province of Pontus and Thrace suffer from cold or frost if they go on for six weeks after midwinter without a break; but both in that region and in the remaining parts of the world, a heavy frost coming immediately after the trees have produced their fruit kills them even in a few days.

Kinds of damage due to injury done by man haveEffects of damage especially to bark. effects proportionate to their violence. Pitch, oil and grease are particularly detrimental to young trees. To strip off the bark all round trees kills them, except^a in the case of the cork tree, which is actually benefited by this treatment, because the bark thickening stifles and suffocates the tree; nor does it do any harm to andrachne^b if care is taken not to cut into the body of the plant as well. Beside this, the cherry, the vine and the lime shed some bark, though not the layer next to the body which is essential to life, but the layer that is forced outward as another forms underneath it. The bark of some trees, for instance planes, is fissured by nature. That of the lime after it is stripped grows again almost in its entirety. Consequently with trees the bark of which forms a scar, the scars are treated with mud and dung, and sometimes they do the tree good, if the stripping is not followed by a period of exceptionally cold or hot weather. But some trees, for instance hard oaks and common oaks, die, but rather slowly, under this treatment. The time of year also matters; for instance if a fir or a pine is stripped of its bark while the sun is passing through the Bull or the Twins, when they are budding, they die at once, whereas if they undergo the same injury in winter they endure it longer; and similarly the holm oak,