HARDENING AND ADAPTATION 



The problems that arose in this line of work 

 were among the most difficult he had ever 

 encountered. Very much had to be taken into 

 account, the past of the tree, not only imme- 

 diate but remote, its failures and successes 

 under different environment influences, its 

 limitations, its need of new blood by crossing 

 or the restoration of its depleted veins through 

 selection. For Mr. Burbank had come to look 

 upon all plant life as being very closely allied 

 to the life of man, open to many similar 

 attacks, subject to many diseases, needing the 

 keen eye of the physician and the dietarian, 

 responding to heat and cold, light and shadow, 

 inactivity and exercise. He early recognized, 

 too, the importance of transference, the intro- 

 duction of a fruit from a distant quarter of the 

 globe, engrafting its life upon the life which 

 was not coming up to its opportunities. He 

 recognized that that which holds true in the 

 human race, that admixture of blood is desir- 

 able, indeed is imperative at intervals, in order 

 to prevent such physical decadence as follows 

 the intermarrying of royal families, held 

 true sometimes in the vegetable world; there 

 were certain families that needed new blood 



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