524 
pliisiy's natural history. 
[Book XVIT. 
iDjuries inflicted by the hand of man are productive also of 
bad effects. Thus, for instance, pitch, oil, and grease,^ if ap- 
plied to trees, and young ones more particularly, are higlily 
detrimental. They may be killed, also, by removing a circular 
piece of the bark from around them, with the exception, in- 
deed, of the cork-tree,^ which is rather benefitted than other- 
wise by the operation ; for the bark as it gradually thickens 
tends to stifle and suffocate the tree : the andrachle,^^ too, re- 
ceives no injury from it, if care is taken not to cut the body 
of the tree. In addition to this, the cherry, the lime, and the 
vine shed their bark not that portion of it, indeed, which is 
essential to life, and grows next the trunk, but the part that 
is thrown off, in proportion as the other grows beneath. In 
some trees the bark is naturally full of fissures, the plane for 
instance : in the linden it will all but grow again when re- 
moved. Hence, in those trees the bark of which admits of 
cicatrization, a mixture of clay and dung^^ is emploj^ed by way 
of remedy ; and sometimes with success, in case excessive cold 
or heat does not immediately supervene. In some trees, again, 
by the adoption of these methods death is only retarded, the 
robur and the que reus, for example. The season of the year 
has also its peculiar influences ; thus, if the bark is removed 
from the fir and the pine, while the sun is passing through 
Taurus or Gemini, the period of their germination, they will 
instantly die, while in winter thay are able to withstand the 
injurious effects of it much longer : the same is the case, too, 
with the holm-oak, the robur, and the quercus. In the trees 
above mentioned, if it is only a narrow circular strip of bark 
that is removed, no injurious efl'ects will be perceptible ; but 
in the case of the weaker trees, as well as those which grow in 
a thin soil, the same operation, if performed even on one side 
only, will be sure to kill them. The removal of the top,^^ in 
^ He probably means if applied to the hark of young trees. 
s The cork-tree forms no exception to the rule— if a complete ring of 
the bark that lies under the epidermis is removed, the death of the tree is 
the inevitable result. See B. xvi. c. 13. 
10 Probably the Arbutus integrifolia. See B. xiii. c. 40. 
1^ This in reality is not the bark, but merely the epidermis, which is 
capable of reproduction in many trees. ^2 gg^ c. 16 of this Book. 
13 This method^ however, is often found efficacious in preserving the life 
of the oak, as well as many other trees, by excluding the action of the 
air and water. 
1^ It prevents them from increasirjg in height, but does not cause their 
death. 
