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Equatorial Province.—In the southern districts of the Bahr-el-Gazal and

Mongalla Provinces are found purely tropical conditions with a mean precipita-

tion 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.