THE CACTUS AND THE DESERT 



By Willard N. Clute. 



CCORDING tO' the idea of evolution held by adherents 



of the Darwinian theory, the cactus is the response of 

 vegetation to desert conditions. Its thorns and spines are re- 

 garded as defenses originated by the plant for the protection of 

 its edible pulp and precious moisture. It is looked upon as a 

 case of the survival of the fittest. Plants not heavily enough 

 armed to resist the attacks of grazing animals are supposed to 

 have perished long ago, leaving only the most resistant to 

 populate the desert. 



While it is certainty true that the cacti are excellent illus- 

 trations of the survival of the fittest, they probably did not 

 attain their present forms in just the way that the earh- evolu- 

 tionists imagined. It is no longer believed that they have 

 originated by gradual change helped on b}^ the animals that ate 

 the less efiiciently armed. Thc}^ probably first appeared about 

 as we find them now. Probably, also, these forms did not arise 

 in the desert but originated on the edge of it in response to 

 various conditions. It should be remembered that the strug'gle 

 for existence is not alone the struggle for sufficient moisture. 

 Lack of light will as surely kill green plants as lack of water. 

 In the desert light is always abundant. Given, then, a plant 

 that can endure long sieges of drouth it may find the dryer 

 regions of the ^earth desirable places of residence. Probabty 

 the cactus moved into the desert because the struggle for exist- 

 ence was less strenuous there. Too much water is as bad for 



