698 THE UNIVERSE. 



penetrable nature. There, according to Humboldt, exist 

 some which occupy a space of 16,000 square leagues. 



Grasses and leguminous plants cover the surface as far 

 as the eye can see. In other places the steppe bristles 

 with tall thistles, which form impenetrable spiny barriers. 



The steppes of Southern America, being covered Avith a 

 light clothing of plants, and being periodically inundated 

 by torrents of rain, often present a luxuriant growth of 

 grasses. These solitudes are at such times traversed by 

 legions of animals, which there find water and an ample 

 supply of nourishment. 



But the scene changes so soon as the drought sets in. 

 Then death and aridity appear everywhere. The tropical 

 heat allows only a very ephemeral duration for this luxu- 

 riant vegetation. When the heat of the sun is no longer 

 tempered by the rains, and when he darts his vertical rays 

 upon the steppe, the marshes are soon dried up, all the 

 plants Avither and turn to dust, and a sea of ashes succeeds 

 to an ocean of verdure. The extreme heat stupifies the 

 crocodile and the boa-constrictor; like the hybernating 

 animals of the polar regions, they sink into the mud and 

 remain there motionless till the return of the rains. All 

 the animals express their sufl'erings by deep groans, a few 

 only understand how to quench their thirst Avith the succu- 

 lent stems of certain Cacti, the spiny armour of which tears 

 their mouths and makes them bleed. ^ 



^'■The mules," says Humboldt, ''more eircuiuspeet ami wily, endeavour to 

 satisfy their thirst in another manner. A plant of sjiherieal form and bearing, 

 numerous flutings, the Melocaotus, contains a very watery pulji under a spiny 

 envelope; the mule, by means of its fore-feet, separates the spjines, puts down its 

 mouth carefully, and \'entures to drink the refreshing juice. But it cannot always 

 drink at this living vegetable spring without danger. Animals ai'e often seen 

 which have been lamed in the hoof by the spines of the cactus. 



" To the burning heat of day succeeds the freshness of the night, which equals 

 the day in duration; but the cattle and horses cannot even then enjoy repose. 



