138 LUTHER BURBANK 



the desert finds it necessary to conserve water. 

 So through natural selection the cactus developed 

 the custom of dropping its leaves when they were 

 only tiny bracts, at the very earliest stage of its 

 growth, developing chlorophyll bodies in its slabs 

 to perform the functions usually performed in 

 the leaf of the plant. 



These present a relatively small surface to the 

 air in proportion to their bulk, and conserve in 

 large measure the water that would be transpired 

 from an ordinary leaf system. 



This, combined with the habit of the cactus of 

 sending its long, slender roots deep into the soil, 

 accounts for the power of the plant to grow in 

 arid places. 



It is not that the cactus can perform its life 

 functions without water any better than can an- 

 other plant. It is only that the cactus has learned 

 how to seek a water supply in the depths, and to 

 conserve it after it has been found. 



What the cactus does then, essentially, is to 

 bring water from the depths of the parched 

 earth, and to store it in its flat slabs, along with 

 nutritious matter, so that these constitute both 

 food and drink for the animal that eats them. 



It is obvious that a plant that has such charac- 

 teristics, now that it has been relieved of the 

 spines that were hitherto its greatest drawback, 



