Postscript xix 



ciently broken up, provided that it contains the chemical elements of fertility ; so that 

 the agricultural or grazing value of any particular spot often affords no indication of 

 its value for tree-planting. 



Though the world has now been nearly everywhere explored, and the number 

 of trees capable of growing in Great Britain has been more than doubled by fresh 

 introductions since Loudon wrote in 1838, it is very surprising how few, if any, of 

 the newer introductions seem likely to supersede or even to equal our long-tried 

 native and introduced trees. Though no one can be a stronger advocate than I am, 

 both ii principle and in practice, of the planting of a great variety of exotic trees, 

 and though in localities where somewhat unusual conditions are found, some of these 

 species such as Japanese larch, Sitka spruce, Lawson and Nootka cypress, and 

 Douglas fir do seem likely to be more profitable than older introductions like the 

 European larch. Silver and Spruce firs, yet I can hardly think of any broad-leaved 

 tree, except some poplars which are not yet fully proved, and possibly the grey 

 alder, which seems likely to have much economic value or to supersede our native 

 oak, beech, ash, elm, and sycamore, which to timber merchants are at present the 

 only trees really worth looking at, and which will grow to a large size in almost all 

 parts of our islands. Whether time; will prove this to be a fact or not, we have done 

 our best to describe every tree as yet introduced, with the exception of some of the 

 latest introductions from China. 



When trees have passed the age of maturity and are beginning to decline in 

 health they usually show it by the death of the upper branches, which is particularly 

 noticeable on very heavy or very dry soils after a long hot summer. If there is no 

 serious decay in the trunk, this decline may often be checked, for a considerable time 

 at any rate, by a top-dressing of leaf-mould mixed with old rotten manure and fertile 

 soil, spread about three inches deep over the area covered by the branches ; but such 

 dressing must not be too thick or too strong, especially in the case of conifers, for 

 which pure leaf-mould is perhaps the best manure. When wounds caused by broken 

 branches, fungi, or other injuries appear on the trunk, it is important to fill them as 

 soon as possible. The same principles adopted in filling decayed teeth are perfectly 

 applicable to trees, namely, to clear out all decayed wood as far as possible, to apply 

 an antiseptic to the exposed surface, to fill up the cavity with cement, and to cover 

 with lead any cracks or holes by which water can get into the trunk. When branches 

 become dangerous or inclined to split off, they are often supported by iron rods, 

 bands, and chains ; and I believe that when this is done in such a way that the band 

 can be loosened as the branch thickens, it is a safer and more permanent method 

 than passing a rod through a hole in the branch and putting a nut on it to keep it 

 in place. 



There are many other special points in the cultivation of trees which only ex- 

 perience can teach, though the general principles are given in works on forestry and 

 arboriculture ; and in many cases these special points are dealt with in the pages of 

 our work. Opinions vary and always will vary as to the best systems of planting, 

 and the best mixture to adopt, which depend on the peculiar conditions we have to 

 deal with ; but in tree-planting, whether for economic or other objects, it cannot be 



