230 DISEASES OF TREES 



Should the loosened cortex be supplied with nourishment by 

 remaining in organic union with the tree, new tissue may of 

 course also be formed on its under surface, to which some 

 cambium will also have adhered. In such a case the process of 

 cell-division proceeds normally in the cambium, after it has been 

 converted as explained above into short-celled cambium. It is 

 in this way that the new tissues have been formed during the 

 two years which have succeeded the loosening of the flaps of 

 bark, e e (Fig. 134). 



The wood which is formed on the surface of the exposed wood 

 of the stem and on the inner surface of the detached bast is 

 distinguished from ordinary wood by its abnormal structure, 

 and especially by the shortness of its cells and the absence or 

 scarcity of vessels. H. de Vries, 1 who was the first to direct 

 attention to this abnormality, designated such wood with the 

 name " Wound-Wood." 



The formation of new cortex in the manner above de- 

 scribed has been made use of on a large scale in the cultiva- 

 tion of cinchona bark under Maclvor's system. Strips of 

 cortex several yards long are separated from the wood along 

 the cambium zone, alternate strips of the same breadth being 

 left in situ. The whole is then covered with moss. The 

 system can only be practised during the rainy season. The fresh 

 growth contains twice as much quinine as the original bark.* 



When the cambium on the portion of a stem that has been 

 deprived of its cortex dries up before it can produce an invest- 

 ing layer, or should cambium be entirely absent from the sur- 

 face of a wound, as, for instance, in the case of branch-wounds, 

 &c., the only regenerative process that is possible is the 

 formation of callus from the edge of the wound. 



Under the so-called Javanese method the cortex is removed, 

 with the exception of a thin layer which contains the cambium 

 and youngest bast. In a short time a layer of periderm forms 

 beneath the surface, and prevents the loss of moisture. By this 

 method, which may be practised at all seasons, the tree does not 

 require to be bound round with moss. 



1 Hugo de Vries, Ueber Wundholz, Flora, 1876. 



* [This system of "mossing" has been much in vogue among the planters 

 in Ceylon. ED.] 



