From the text...'The paper deals with the effects of wet and dry seasons, leaching and drainage effects on slopes, the effects of fires, leaching on burnt ground, the process of recovery from burning, the alterations in some physical properties of the soil on burning and the soil characteristics of special ecological zones. The first characteristic of the soils in general is their very high acidity, the mean pH for an extract of 5 gm. soil in 20 c.c. of water being 3.4 for 2-inch depths and 3.9 for 9-inch depths. The 9-inch depths are almost invariably less acid than the 2-inch. The range of pH is 3.9-2.3 for 2-inch depths and 4.7-3.1 for 9-inch depths. In dry and wet seasons the greatest variations in the coefficient of humidity are found in surface layers on high ground and the least variations in surface layers in the valleys. The 9-inch depths are intermediate, the tops again varying more than the valleys. On old ground a wet season leads to a loss of salts by the tops and a considerable gain in the valleys. 9-inch layers, however, do not gain at the expense of the 2-inch layers. Fires lead to the destruction of 60 per cent of the original humus in relatively young heath but only about 30 per cent. in older heath, where the soil is particularly rich in humus. The colloidal properties of the organic matter which remains are always much impaired. Drainage of salts into the valleys becomes more pronounced, and the 9-inch layers in the valleys at least do now show a considerable increase at the expense of the salts lost by the high ground and surface layers. The total salts are at first increased but are then rapidly leached out until well below normal. They continue to fall through further leaching until a late stage in recolonisation (possibly for six to eight years), when sufficient new humus is formed to check the process. The valleys are probably more hospitable for recolonisation through their higher salt content gained by this drainage. The acidity is always decreased by a fire and owing to the equalisation of texture becomes more similar at the 2-inch and 9-inch depths. During recovery from burning there is a gradual increase in humus and acidity and lastly in salts. The increase in acidity is more rapid in the valleys, so that the bottoms of the slopes come again to be considerably more acid than the tops. A factor aiding the production of relatively high acidity in the valleys may be the reduction in the ameliorating drainage effects through the greater accumulation of humus. A method is developed for the quantitative evaluation of the extent of leaching and drainage effects on slopes as shown by the changes in the ratio of salts to humus at different levels. Laboratory experiments show that water and salts pass more readily through burnt than unburnt soils and that absorption of salts is diminished by burning. A greater loss by leaching and drainage would therefore be expected on burnt than on unburnt areas. This is found in practice. The soil characteristics of special ecological zones such as areas dominated by Erica tetralix, Ulex nanus, Pteris aquilina and Vaccinium or in which Molina or Aira (Deschampsia) flexuosa become prominent features are briefly discussed and can be gathered from Table XV. The results for certain zones of poor vegetation, gravel and bare patches, and concerning the distribution of potassium and aluminium are also given in the text.'