— 8 — Equatorial Province.—In the southern districts of the Bahr-el-Gazal and Mongalla Provinces are found purely tropical conditions with a mean precipitation exceeding 1,000 mm. It should here be possible to extend largely the existing areas planted to sugar, rubber, coffee and tobacco and to introduce tea.

Such products, from their intrinsic value, could carry the necessarily heavy costs of haul to port of shipment. Rice would ultimately constitute the chief grain food of the native population.

Agricultural Research.

Financial considerations have very unfortunately limited the work of agricultural research to a systematic examination of the problems of riverain irrigation in the northern provinces. Rain-farming in the southern districts, basin irrigation, the breeding and management of improved types of livestock, dairy and poultry farming, horticulture and other subsidiary branches of the agricultural industry still await attention and development. An attempted exploitation of the Northern Sudan with its negligible rainfall, excessive mean temperature, high winds, abnormal evaporation, cutting desert sands, absence of natural grazing and scanty fuel supplies can only be justified by the relative advantages of railway transport and access to a deep-water harbour. Whether these features sufficiently ofEset the economies in production offered by an ample rainfall, equable climate, good grazing and timber, as found in the south, can only be determined by experiment and the possibilities of railway extension and improvement in river transport.

The Desert Environment.—Thecultivation of crops of economic value can be effected in the Northern Sudan only by the artificial modification of a desert climate and soil, in which naturally nothing but the scantiest vegetation can exist. Such vegetation has a xerophjrtic character and structure. Here and there are dotted little greyish-green plants with large intervening stretches of soil utterly devoid of plant life. Only when a shower of rain moistens the surface do numerous annual herbs germinate, bear fruit and die a few weeks later. Perennial plants show a number of structural features which are adaptations to an exceptional qped for protection against unfavourable conditions. They may include diminution in size, or suppression, of leaves, thick-walled epidermis and strong development of cuticle, hairy coating, thorns, the production of aqueous tissue for water storage, and excessive development of the fibrous and woody elements. Neither rapidly of growth, scattered distribution nor such morphological features are compatible with profitable cultivation, and a new environment must be created to meet the requirements of commercial agriculture.