In consequence of the repeated burnings of the steppes, well-nigh all vegetation was now blighted and impoverished: in particular the higher districts presented an appearance of wretched desolation. Repeatedly, in the winter landscape of the tropics, there are seen trees standing in full foliage in the very midst of their dismantled neighbours; and the loss of leaf would seem to be hardly so much an unconditional consequence of the time of year as a collateral effect of locality or condition of the soil. After having for months together explored every thicket, and day after day penetrated into the high grass on the river-banks, I could not suppress my astonishmant at the absence of every description of snakes. The Khartoomers suggest an explanation of this circumstance which I am not disinclined to accept; they conjecture that in this stony region there is a deficiency of that rich black soil which splits like a glacier in the dry season, and makes riding in the North-Eastern Soudan a very dangerous proceeding; and, consequently, that there is neither a way for snakes to escape from the fires of the blazing steppes, nor any of those lurking-places which are indispensable for their resort. [Sidenote: STEPPE-BURNING.] Incalculable in its effect upon the vegetation of Central Africa must be the influence of the annual steppe-burning, which is favoured by the dryness of the seasons. The ordinary soil becomes replaced by charcoal and ashes, which the rain, when it returns, as well as the wind, sweeps right away into the valleys. The rock is, for the most part, a very friable and weather-worn ironstone, and upon this alone has everything that grows to make good its footing. The distinction, therefore, as might be imagined, is very marked between vegetation under such conditions, and vegetation as it displays itself by the banks of rivers, where the abundant grass resists the progress of the fire, and where, moreover, a rich mould is formed by the decay of withered leaves. But even more than the impregnation of the soil with alkalies, does the violence of flames act upon the configuration of plants in general. Trees with immense stems, taking fire at the parts where they are lifeless through age, will die entirely; and, where the grass is exceptionally heavy, the fresh after-growth will perish at the roots, or in other places will be either crippled or stunted. Hence arises the want of those richly-foliaged and erect-stemmed specimens which are the pride of our own forests; hence the scarcity of trees, which are either old or well developed; and hence, too, the abnormal irregularity of form which is witnessed at the base of so many a stem and at the projection of so many a shoot.