198 ON THE EFFECTS PRODUCED ON TREES AND SHRUBS 



with fresh soil over the roots and shrubberies occasionally. The 

 first is rendered absolutely necessary by the confined circulation 

 of air in town situations and vitiated conditions of the atmosphere, 

 combined with tlae frequent absence of light in sucli localities ; 

 and which is so essential an element in tree-growth. The second 

 suggestion is proposed, with a view to the proper balance of head 

 and due development of upright stem, and to prevent a flat- 

 headed habit being acquired, to which trees in such sites are 

 extremely prone — a habit which results in one or more of the 

 stronger-growing side branches outrunning their neighbours and 

 interfering with the upright form of the tree. Branch and stem 

 pruning, and foreshortening the upper tiers of branches in the 

 head, will be found most beneficial in trees so situated, when 

 about from twelve to twenty feet in height ; although gentle 

 hand pruning should be commenced at a much earlier stage in 

 their growtli. The third recommendation we have made is a very 

 important one to all trees which suffer from the smoke about 

 towns, and although the moisture of our climate and frequency 

 of rains mitigate to some extent the evils produced by the sooty 

 deposits, nevertheless much may be done by judicious watering, 

 especially to shrul)S. A short supply of water at tlie roots, 

 causing the premature shedding of the leaves before they have 

 fulfilled their functions — a process which they require longer 

 time to perform, owing to their vitiated and debilitated condition 

 rom the smoke and soot — is the principal cause of disease and 

 stunted growth of town trees. Drains, both surface and under- 

 ground, and hard paved streets, and walks impervious to water 

 in the vicinity of tree roots, — as must lie the case more or less in 

 all large towns, — draw off the rainfall which in natural circum- 

 stances would go to supply the root moisture, and consequently 

 in most situations of the nature referred to, only a very limited 

 quantity ever reaches the rootlets and spongeoles at all. Thus 

 summer watering and a thorough soaking, in dry, dusty weather, 

 which could be quite easily accomplished in any town public 

 gardens by the aid of the fire brigade engines, would be of immense 

 value in restoring the proper equilibrium of moisture and health to 

 the plants in such places, and an experiment which would repay 

 itself in the enhanced amenity of the walks and gardens. The 

 fourth and last sufjgestion made for the amelioration of tree and 

 shrub culture in smoky localities, namely, — top-dressing the roots 

 occasionally with fresh loam, is rendered necessary in such 

 situations, by the loss which the soil sustains every season by 

 the removal of the fallen leaves which in ordinary circumstances 

 in the forest or park, would go to nourish and refresh as manure the 

 surface of the ground, whence the decomposed ingredients are 

 carried down by the winter's rainfall and action of frost into the 

 soil, forming food for those young rootlets near the surface, which, 



