46 ANIMAL LIFE IN DESERTS 



Jordan VaUey, and in certain spots round the 

 margin of the Dead Sea. The soil here is so im- 

 pregnated with salts that in spite of an annual 

 rainfall of 16-18 inches, and in spite of the excellent 

 surface drainage provided by these slopes, no 

 vegetation exists. My friend, Mr. Raczkowski, of 

 the Department of Agriculture, Palestine, made 

 an analysis for me of the surface soil of one of the 

 hillocks shown in the plate ; the analysis was made 

 in February, just after the winter rains which one 

 might suppose would have washed much of the salt 

 out of the superficial layer of soil. Nevertheless, 

 the analysis revealed the presence of 0*58 per cent 

 of sodium sulphate, 0*57 per cent of sodium chloride, 

 and 36-13 per cent of sodium carbonate. Any 

 one of these salts in such high proportions would 

 be sufficient to prevent the growth of plants, except 

 forms specially adapted to exist on salt soils : their 

 united effect is to render these clay hills abso- 

 lutely devoid of plant life at all seasons of the 

 year. 



The loess of Transcaspia and Turkestan and the 

 fine silt of the plains of Lower Mesopotamia are 

 very fertile if they are irrigated and if provision 

 is made for the removal of the water after it has 

 flowed upon the land, so that mineral salts do not 

 accumulate unduly. In Southern Mesopotamia the 

 rainfall is not inadequate, and combined with the 

 annual flooding from the Tigris and Euphrates 

 would be sufficient to sustain considerable vegeta- 

 tion, were it not for the physical peculiarities of 

 fine silt. Here, in fact, we have country which 



