STEPPES AND DESERTS. 37 



with cold, so here, under the influence of the parching drought, the 

 crocodile and the boa become motionless and fall asleep, deeply 

 buried in the dry mud. Everywhere the death-threatening drought 

 prevails, and yet, by the play of the refracted rays of light producing 

 the phenomenon of the mirage, the thirsty traveller is everywhere 

 pursued by the illusive image of a cool, rippling, watery mirror. ( 36 ) 

 The distant palm bush, apparently raised by the influence of the 

 contact of unequally heated, and therefore unequally dense, strata of 

 air, hovers above the ground, from which it is separated by a narrow, 

 intervening margin. Half concealed by the dark clouds of dust, 

 restless with the pain of thirst and hunger, the , horses and cattle 

 roam around, the cattle lowing dismally, and the horses stretching 

 out their long necks and snuffing the wind, if haply a moister current 

 may betray the neighborhood of a not wholly dried up pool. More 

 sagacious and cunning, the mule seeks a different mode of alleviating 

 his thirst. The ribbed and spherical melon-cactus ( s7 ) conceals under 

 its prickly envelope a watery pith. The mule first strikes the 

 prickles aside with his fore feet, and then ventures warily to approach 

 his lips to the plant and drink the cool juice. But resort to this 

 vegetable fountain is not always without danger, and one sees many 

 animals that have been lamed by the prickles of the cactus. 



When the burning heat of the day is followed by the coolness of 

 the night, which in these latitudes is always of the same length, even 

 then the horses and cattle cannot enjoy repose. Enormous bats suck 

 their blood like vampires during their sleep, or attach themselves to 

 their backs, causing festering wounds, in which musquitoes, hippo- 

 bosces, and a host of stinging insects, niche themselves. Thus the 

 animals lead a painful life during the season when, under the fierce \ 

 glow of the sun, the soil is deprived of its moisture. At length, 

 after the long drought, the welcome season of the rain arrives; and J 

 then how suddenly is the scene changed ! ( 38 ) The deep blue^of the ( 

 hitherto perpetually cloudless sky becomes lighter; at night the 

 dark space in the constellation of the Southern Cross is hardly dis- 

 tinguishable; the soft, phosphorescent light of the Magellanic clouds 

 fades away; even the stars in Aquila and Ophiucus in the zenith 

 shine with a trembling and less planetary light. A single cloud 

 appears in the south, like a distant mountain, rising perpendicularly 

 4 



