Deserts 



from the injured surface, at once covers over and gums 

 up the scar, so that but little water can be lost through 

 a wound. 



Against the browsing animals, which swarm in such 

 country, they are especially well protected by thorns of 

 a formidable character, or in some Australian cases by 

 their bark, which contains some 26 to 48 per cent, of 

 astringent tannin. 



When one visits the acacia scrub in those rare places 

 where it is still in its natural condition, scarcely traversed 

 except by some wandering slave-raider or roving Bedouin, 

 it is the abundance of game that impresses every traveller. 



Herds of zebra, ostriches, the gaunt and indescribable 

 babiroussa, large-eared and long-necked gazelles, and 

 other antelopes may or used to be seen continually. This 

 was the case, e.g., in the Taru desert of East Africa. 

 Hunting is difficult, for the long necks of many of the 

 animals are quite invisible against the dull yellowish- 

 brown background, so that they can see long before they 

 can be seen by the sportsman. In such places it is more 

 than probable that in the struggle between plant and 

 grazing beast it is the first that is gaining. 



Those animals, not improbably, assist rather than in- 

 jure the vegetation. Their manure is scattered over 

 the dry soil, which is for the most part entirely of 

 mineral origin, and makes it a better and richer loam 

 (see p. 198). 



Such acacia scrub is extraordinarily variable. In 

 some places it is almost a forest with closely set trees ; 

 elsewhere the trees are scattered, and the ground be- 

 tween them is dotted with scanty tufts of wiry grass 

 or sedges. Especially near the desert proper one may 

 find an (l orchard steppe," so called from the scattered 

 little trees, about 20 to 30 feet high, which are not 

 unlike apple or pear trees. 



178 



