Deserts 87 



it is enabled to bear the drought by the fact that it has 

 huge roots, which weigh hundreds of pounds when the 

 tree is only a few feet high. 



But the prickly-pear cactus is almost equally useful, so 

 far as the cattle are concerned, and it covers prairies so 

 vast that the supply is simply inexhaustible. In spite 

 of drought, and heat, and dry soil, the thick, stem-like 

 leaves, or leaf-like stems, hold an enormous quantity of 

 moisture, and when the thorns have been burned off even 

 sheep can live and grow fat upon it. For horses and 

 cows it is split open, and they eat out the inside, which is 

 so succulent as to answer the purpose of drink as well as 

 food. One can hardly imagine any other way in which 

 water could be so successfully stored in these arid districts 

 as within the thick, leathery skin of the cactus. 



But the gourd family are almost as wonderful in the 

 way in which they manage to appropriate and keep pos- 

 session of water, even under the driest circumstances. 



A pumpkin is all water, with the exception of five and 

 a half per cent of its weight, and yet large pumpkins may 

 be seen growing in what looks like nothing but sand. To 

 be sure, their thick rinds enable them to keep the water 

 when they get it, and sand is liberal in the way of parting 

 with its moisture; but even so, knowing how very watery 

 they are, it is strange to see them growing in such dry soil. 

 Plants of this kind, however — gourds and melons — are 

 especially characteristic of so-called ''desert" regions, 

 which are exposed to long-continued droughts. 



Whenever there is more rain than usual vast tracts of 

 desert land in South Africa are covered with melons, 

 which provide food and drink both for man and beast. 

 The sama, or wild water-melon of the Kalahari, grows in 



