BOOK XVII. xx.v\ii. 233-235 



in the northern countries Uke the provincc 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 have Effects of 

 effects proportionate to their violence. Pitch, oil ^^"^*fy ^^, 

 and grease are particularly detriniental to young '""■*• 

 trees. To strip off the bark all round trees kills 

 them, except" 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 anv harm to andrachne ** if care is taken not 

 to cut into the body of the plant as well. Beside 

 this, the clierry, the vine and the lime shed some 

 bark, though not the layer next to the body which 

 is essential to life, but the laver that is forced out- 

 ward as another forms underneath it. The bark of 

 some trees, for instance planes, is fissured by nature. 

 That of the Hme 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 foUowed by a period of excep- 

 tionally cold or hot weather. But some trees, for 

 instance hai-d oaks and common oaks, die, but rather 

 slowly, under tliis 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 

 tlie Twins, when they are budding, they die at once, 

 whereas if they undergo the same injury in winter 

 they endure it longer ; and simihirlv the holm oak, 



163 



