ENVIRONMENT 79 



The hundred, stronger than the rest, though 

 eaten to the ground were able still to send up 

 new leaves, and with each new crop the hairs 

 became stiffer and longer, the protuberances 

 harder and more pointed, until finally, if there 

 were even only one surviving representative of the 

 race, there was developed a cactus which was effec- 

 tually armored against its every animal enemy. 



One such surviving cactus, as transformed 

 throughout ages of time, meeting new conditions 

 with changes so slight perhaps as to be almost 

 imperceptible, but gradually accommodating it- 

 self to the conditions under which it lived and 

 grew one such survivor out of all the billions 

 of cactus plants that have ever grown would 

 have been sufficient to have covered the deserts of 

 America with its progeny to have produced all 

 of the thorny cacti which we have on earth to-day. 



The cactus did not prepare in advance to meet 

 an enemy it simply adapted itself gradually to 

 changing environment as all vegetable and 

 animal life on the earth must or perish. First, 

 surviving the desert drought and the broiling 

 sun, it threw its roots deep into the earth for the 

 scanty moisture. Then, attacked by enemies 

 which ate off the leaves, it still had life and re- 

 sistance to try again. Ineffectually, at first, it 

 began to build its armor, but each discourage- 



