Probably no work connected with horticulture requires more judgment and good management than the planting of trees and shrubs in urban districts. The materials and soil of which streets and town gardens are usually formed are ill fitted for sustaining a healthy condition in trees and shrubs for any length of time. This fact, coupled with the impurities of the atmosphere in densely populated centres, has to be constantly borne in mind. In more favourable districts all that is necessary is to open a pit of sufficient size to contain the roots of the tree or shrub to be planted; but in towns the soil, often hard as iron and composed mainly of refuse building materials, contains but little plant food. For many years past careful observations have been made, not only in London, but in Glasgow, Liverpool, Manchester, Warrington, and Dublin, as to which trees and shrubs succeed best in the most smoky localities of each town, and it is mainly by tabulating these different experiences that satisfactory information on the subject has been obtained. Coal smoke from the chimneys in the larger and more crowded centres of industry is no doubt bad enough, but, when we have to contend with an atmosphere that is largely impregnated with the outcome from chemical, gas, or iron works, the difficulties to be encountered are correspondingly increased.

The injurious effects of smoke have become much more pronounced during the past century, and Sir William Richmond, R.A., told the annual meeting of the Coal Smoke Abatement Society last year that Westminster Abbey had suffered from more rapid decay in the last hundred years than in all the previous centuries of its existence. The chief cause of the destruction of the stonework has been shown to be the presence in the air of sulphur acids: the stone is converted into sulphate of lime; in the process of its formation this disintegrates the stone by expansion. The connection between smoke and stone decay appears to be invisible gases emitted from the smoke particles.

If stonework suffers so at the hands of smoke and sulphuric and other acids, what, it may be asked, must the effect be on the foliage of trees and shrubs - particularly such as are planted in the most smoke-infested parts of our great towns and cities? When compared with Continental cities - Paris, Brussels, or Berlin - where tree culture is carried out most successfully, the atmosphere of British towns is impregnated to a far greater extent with noxious fumes. Dry low-lying and confined areas, particularly where excessive heat and atmospheric impurities are present, are decidedly the worst, while open and high-lying districts, though in the centre of a town, offer fewer difficulties.

That certain trees and shrubs succeed best in particular towns is a well known fact, and the smoke-proof London Plane is by no means the best tree for some of the colliery districts; in Sheffield, for instance, its place is largely taken by the Canadian Poplar. In Manchester, the Lime would appear to thrive best, after which the Elder, Thorn, and Plane succeed in the order named. The variegated leaved Sycamore and the Horse Chestnut are favourites where the smoke from collieries is most offensive. But many such cases could be pointed out, and even in the case of bedding plants certain species succeed best in particular localities. In the gardens about the Royal Mint, and where exposed to the deleterious fumes from gold-refining works, Fuchsias do remarkably well; indeed, the dwarf edging variety, Golden Treasure, thrives so well that advantage has been taken of the fact to propagate some of the stock that is annually required for one of the London parks from cuttings taken at the Mint. In the East End of London the Creeping Jenny (Lysimachia) thrives well as a window plant, while in the chemically impure atmosphere of Lambeth one of the Veronicas is the favourite plant for indoor culture. The St. John's Worts (Hypericum) do not as a rule thrive well in London; yet around the Tate Gallery, which is only divided by the river from the Lambeth pottery district - the worst in the metropolis for atmospheric impurities - one species at least flourishes amazingly, and has produced flowers in abundance for many years past; while, at St. Paul's Churchyard, the lesser Periwinkle (Vinca minor) has become quite established and runs about freely. In Chancery Lane, at the Record Office, the common Ivy, Bladder Senna, and Yucca do best. In other parts of London two well known varieties of Campanula are largely grown as pot plants. It is a somewhat strange fact, too, that some varieties of trees and shrubs succeed better than the type species in smoky localities, as witness the London Plane (a variety of Platanus orientalis), variegated-leaved Sycamore, Fastigiate Poplar, two varieties of Pyrus, Weeping Elm, Weeping Ash, and several varieties of Acacia, notably Robinia Pseud-Acacia inermis and R. Pseud-Acacia Bessoniana.

Similarly,amongst shrubs,we have the dwarf Holly, golden varieties of Euonymus, Privet, and Ribes, the double-flowered Gorse, Euonymus radicans variegata, and others. With Grasses, too, some curious experiences might be related. At the British Museum the Yarrow completely ousted the Grasses from the plots in front of that building, and in the moat of the Tower of London several Grasses that succeed in less smoky parts of the metropolis quickly die out. Near the main entrance to the Tower of London, and close to Billingsgate Fish Market, considerable difficulty was experienced in getting the Plane trees established; though, in the matter of soil and choice of strong, sturdy specimens, everything that could be thought of was accomplished. At last it was found that the drip from the fish carts was the cause of the evil, and a remedy was quickly found.

In another garden, where dust, smoke, and soot are plentiful, the Bladder Campion (Si-lene inflata), Saponaria officinalis, the common Marigold, and Rye Grass seem to positively revel. In situations almost constantly subjected to the sulphurous fumes of the railway engines near Camden Town, and in the poorest of soils, Poa annua would appear to be quite at home. The chemical fumes from the pottery works at Lambeth are well known to act injuriously on vegetation generally, but the Mulberry, Fig, Sycamore,Turkey, and Evergreen Oaks thrive as well there as they do in any part of the metropolis. The fumes given off from many of our City manufactories act most perniciously on vegetation generally - a fact that was brought to my notice by the behaviour of some of our most valuable smoke-resisting trees and shrubs that have been planted in the graveyard at St. Giles-in-the-Fields. Meeting the gardener there I remarked on the wretched condition of the trees and shrubs generally, his quick reply being, "Well! with Crosse & Blackwell's on the one side and Nixey's Black Lead Works on the other it's a wonder there's a living plant left!" Here the common Fig and Black Poplar seemed better able to withstand the atmospheric conditions than either the London Plane or Acacia.