528 LIFE AS RELATED TO PHYSICAL CONDITIONS 



which thousands of years ago sorted the rock materials and 

 built the vast continental ice palaces of the Glacial Period. 



Adaptability of Life. There is hardly a place on the 

 earth's surface not adapted to some form of life. Even upon 

 the ice-bound interior of Greenland a microscopical plant 



and a tiny worm 

 have found a home. 

 The dry desert re- 

 gions have a few 

 plants with small 

 leaves or, like the 

 cactus, with no true 

 leaves. Lack of 

 leaves prevents the 

 evaporation of the 

 water from plants 

 and so protects them 

 from drought. 



Another example 

 of adaptability is the 

 fact that the small 

 animals of the desert 

 are generally of a 

 sandy color, which 

 makes them hardly 

 distinguishable from 

 their desert sur- 

 roundings. The large 

 ones are swift, strong 

 runners, like the an- 

 telope and ostrich, 



CACTI 



These are adapted to desert life because 

 they have no leaves from which water can 

 evaporate. 



