LUTHER BURBANK 



its racial history; and the plant at the cotyledon 

 stage may be regarded as really still an embryo, 

 inasmuch as it is drawing its nourishment from 

 the nutritive matter stored in the seed. 



The first leaf that puts out just above the 

 cotyledons may be spiny or hairy, in recognition of 

 the racial period when spines were worn, even in 

 my new spineless varieties. But the quality of 

 these little spicules will enable the experienced 

 experimenter to determine whether they represent 

 future spines or only a racial reminiscence. 



So it is possible to make first selection among 

 the seedlings at a very early period, and to weed 

 out from among the hundreds of thousands all but 

 a few. 



Unfortunately the cactus requires from three 

 to five years from the seed to come to fruiting time. 

 So the experimenter who is attempting to develop 

 an improved spineless race must wait patiently 

 throughout this long period before he can effect a 

 second hybridization and thus carry his plant one 

 stage farther along the road to the coveted goal. 



But by carefully selecting the seedlings that 

 show the most likelihood of a propensity to pro- 

 duce smooth slabs, yet which at the same time are 

 strong of growth and resistant to unfavorable con- 

 ditions, it is possible to note marked progress even 

 in a single generation. And when the selected 



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