350 PLANT-BREEDING 



are everywhere abundant in richer regions and on more 

 favorable soils? Are the plants of the deserts only such 

 as can endure the hardships of these unfavorable surround- 

 ings, all others being stamped out, as soon as they try to 

 transgress the limits of these peculiar areas? Is not the 

 popular saying that they are cast out, to live on the desert, 

 nearer the truth than the current scientific conception, 

 which regards them as the product of their present environ- 

 ment? 



To my mind the answer to these questions is given by 

 the plants themselves. This answer is: They all prefer 

 more favorable conditions to those which are given them. 

 They endure the desert, but only with difficulty. Their life 

 is nearer starvation than enjoyment. They are multiply- 

 ing themselves in a prodigious manner, not, however, from 

 luxuriance, but on account of the absence of competition. 

 They do not thrive, nor do they unfold their full stature 

 and qualities as they might under better conditions. They 

 greatly prefer irrigated grounds or the moist air of the 

 forest, and only here display their real nature. Even 

 cacti are originally forest plants, and may be seen stoutly 

 growing between densely thronging shrubs. Thus the 

 conviction is forced upon us, that desert-plants are not, 

 as a rule, the product of aridity. They may have originated 

 anywhere else, under any other conditions. But through 

 their peculiar quality of enduring drought, they attained 

 their rapid multiplication as soon as in their migration 

 they reached the arid regions and there found themselves 

 free from competition. 



So it seems to me in all those beautiful cases of fitness 

 for peculiar or extreme influences. We do not know how 

 they have been acquired. We may imagine that usefulness 

 in the struggle for life has preserved some qualities, the 

 bearers of injurious characters being easily stamped out. We 



