ENVIRONMENT 73 



ing and fruiting, not for their own selfish ends, 

 but for us? 



We do not cherish the wild cactus or the 

 poisonous euphorbia. We do not cultivate the 

 sagebrush. 



Is it, then, to be wondered at that the primal 

 instinct of self-preservation has prevailed that 

 what might have been a food plant equal to the 

 apple transformed itself into a wild porcupine 

 among plants? 



That which might have been as useful to cattle 

 as hay changed its nature and became bitter, 

 woody, inedible. 



That which might have been a welcome friend 

 to the weary desert traveler grew instead into a 

 poisonous enemy. 



If the bitterness, the poison, and the spines 

 are means of self-defense, then they must be 

 means which have been acquired. These plants 

 were growing here before their habitation be- 

 came so arid, when animals had an abundance 

 of other food instead of depending entirely upon 

 them; so there must have been a time in their 

 history when they had no need for these various 

 defenses. 



How, in sixteen years, I have carried the 

 cactus back ages in its ancestry, proving satis- 

 factorily by planting millions of cactus seeds 



