RESEARCH AND DEVELOPMENT 49 
When we come to consider the possibilities in arid lands, it is 
recognised that the efforts of individual growers can play but a 
small part in the development of new areas of production or the 
re-establishment of production in great areas which used to be 
fertile in ancient times and are now out of use. I refer to the mil- 
lions of acres in the valleys of the Tigris-Euphrates, the Indus- 
Chenab, and the Nile, in the dry north of Ceylon where still are 
to be seen the remains of ancient irrigation channels and reser- 
voirs. It is estimated that in Latin America over twelve million 
acres are susceptible of development, and an area bigger than 
Egypt’s productive land is said to be available in the middle 
Niger. The re-establishment of these ancient areas and the de- 
velopment of new areas require the joint efforts of research 
institutions, of governments, and the instrumentalities of the 
United Nations, such as FAO, WHO, and WMO, not forgetting 
the international financial authorities. 
Let us now look at some of the problems with which those 
charged with arid land development have to deal. I propose to 
list them under the following heads of water, soils, plants, animals, 
and man, to give you what must obviously be a very sketchy 
outline of some of the salient features of each, and then to come 
to a conclusion. 
Water 
Water is placed first for obvious reasons, and adequate informa- 
tion about the water resources of a region is essential to a safe 
usage of that water for full development in food production, 
domestic use, and industry. In the desert one conserves every 
drop of water for the maintenance of life, in great urban centers 
we turn a tap and water flows, but sometimes restrictions are 
placed on turning those taps. In other lands the fresh water from 
great mountain ranges flows several thousand miles to the sea 
and constitutes a fresh water delta of tremendous size in the 
ocean. 
Rainfall 
Whence comes the supply, great or small? The answer is rain- 
fall, and this is the beginning of what is called the hydrologic 
