122 LUTHER BURBANK 



and allied trees exist to-day in the regions of 

 northern America where they flourish. 



They can withstand the glare of a tropical sun 

 in summer because their ancestors reveled in a 

 tropical climate. And they can withstand 

 equally the arctic cold of winter because their 

 ancestors of other ages were forced to subsist 

 under arctic conditions. 



The versatile trees that, thanks to the racial 

 recollection of these vicissitudes, can adapt them- 

 selves to the inhospitable conditions of our mod- 

 ern climate are but dwarfed representatives of 

 ancient races of giants. To preserve life at all 

 it was necessary for them to conserve their 

 energies; and gigantic growth is feasible only 

 for plants that can send their roots into rich, 

 well-watered soils and can likewise draw sus- 

 tenance perennially from the atmosphere, un- 

 hampered by long periods of dormancy when 

 hfe itself is threatened. 



But these dwarfed races carry in their germ 

 plasm, submerged but not eliminated, factors 

 for giant growth; factors for such development 

 as would adapt them to life in the tropics ; factors 

 also for such development as would adapt them 

 for life in the arctics. 



Their hereditary factors, in a word, are as 

 varied as have been their past environments. So, 



