524 plint's natural history. [Book XVII. 



Injuries inflicted by the hand of man are productive also of 

 bad effects. Thus, for instance, pitch, oil, and grease, 8 if ap- 

 plied to trees, and young ones more particularly, are highly 

 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, 9 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, 10 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 ; u 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 13 is employed 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 quercus, 13 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 they 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 effects 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, 14 in 



8 He probably means if applied to the bark of young trees. 



9 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. 



11 This in reality is not the bark, but merely the epidermis, which is 

 capable of reproduction in many trees. 12 See 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. 



14 It prevents them from increasing in height, but does not cause their 

 death. 



