LUTHER BURBANK 



which now, age on age, became less and less bright 

 as the earth changed the direction of its axis. 



Of course there were other trees that did not 

 undergo this modification. But these were forced 

 either to make more rapid migrations to the south 

 or to give up the fight altogether and to submit to 

 extermination. The only ones that were able to 

 maintain existence in the regions where the cli- 

 mate became exceedingly cold were those that had 

 developed the new type of leaf-form, and had 

 learned to conserve their energies to the last 

 degree. 



But of course the trees that took on this new 

 habit varied among themselves, and as they spread 

 to different regions such variations were developed 

 and fixed under the influence of different environ- 

 ments, until many tribes of needle-leaved trees 

 were developed so differently as to constitute the 

 races that the modern botanist terms pine and 

 spruce and cypress and juniper and hemlock and 

 yew and cedar. 



Representatives of all the chief genera of coni- 

 fers have recognized a place among ornamental 

 trees and are everywhere popular in cold climates. 

 The variations among the different species are so 

 obvious as to attract the attention of the least 

 observant. And the opportunity to develop any 

 fixed new form is correspondingly good. 



[286] 



