THE ADDAX ANTELOPE 1 23 



this cause. Now if the brack of the salt pans con- 

 tain some natural purgative — say crude magnesium 

 sulphate for example — the strange predilection for 

 " salt " admits of a novel explanation. Of course the 

 salt (sodium chloride) is also taken; but magnesium 

 sulphate being one of the commonest impurities of 

 salt may well exist in sufficient quantity to exert a 

 definite physiological action on the digestive tract. 



The Arabs stalk the addax or pursue it on horse- 

 back with the aid of dogs. Their artillery, unreliable 

 and of the gaspipe order, is ably supplemented by 

 the exertions of their beautiful greyhounds — the 

 white silky-coated slottg/ds of the Sahara. The best 

 breed of sloughi comes from Harar, Arba, Hamain, 

 and the Ouled-Nail district: the Sheik el Arab, who 

 resides between Biskra and Tugourt, is said to have 

 the best in the world. Tall, swift, and handsome, 

 these graceful hounds are justly prized; even the 

 poorer nomads often possess one or two degenerate 

 specimens, and the present writer has seen them 

 pacing at the heel of their masters beside long strings 

 of swaying camels on the Biskra- Batna road. In 

 spite of these four-footed helpers the pursuit of the 

 addax is an uncertain occupation: large hunting 

 parties absent for weeks may meet with but scanty 

 reward. The very dunes themselves — some 400 

 feet high — may hide the game. The silvery coat of 

 the quarry also tends to concealment, by harmonising 

 with the shimmer of the heated sand. The wells 



