86 The Great World's Farm 



powerless. On closer examination the coating of "frost" 

 turns out to be composed of innumerable globules of water 

 contained in the surface-cells — the skin — of the leaf. A 

 prick with a needle shows that these globules are just tiny 

 bladders filled with water; but this skin is so exceedingly 

 thin, and so perfectly transparent, that it is a mystery how 

 the plants manage to keep their moisture; and it is often 

 no less a mystery how they manage to obtain it in the first 

 instance. 



An English meadow, again, would wither and turn 

 brown if it were left unwatered beneath the fierce heat of 

 a tropical sun, but the grasses of the Kalahari Desert of 

 South Africa remain surprisingly green, though they get 

 but one or two falls of rain in the course of the whole 

 year. Sometimes they get no rain at all for a twelve- 

 month; but even then, when they are the color of hay, 

 they are equal to hay of ordinary quality as fodder for 

 cattle, and hence are of course still very valuable. The 

 wonder is how they manage to keep any life at all, and 

 any nourishment in them, after so many months of burn- 

 ing drought. 



In parts of Texas, where also rain is quite the excep- 

 tion, the grass is often destroyed during the hot months; 

 but other green things contrive to exist, and these supply 

 its place to the cattle. Timber is scarce in these parts; 

 but within the last twenty years thickets of mesquite 

 have sprung up, and now cover miles of prairie, where 

 formerly there were none. And a most valuable tree 

 the mesquite is, not only for fuel, fences, and for the 

 framework of houses, but for food. Its light foliage 

 takes the place of grass during the hot season, while its 

 beans supply the cattle with abundant food in winter; and 



