64 LUTHER BURBANK 



to unite with others to effect a combination of 

 their heredities. Variation must have been almost 

 inconceivably slow before this era of more eco- 

 nomical combinations of hereditary acquirements 

 occurred. It is progressing to-day more rapidly 

 than ever since plants and animals appeared on 

 the earth. New varieties, new species, and new 

 genera are all now being produced more rapidly 

 than ever since the sun first gave light to the 

 planet. 



The pines and similar plants were developed 

 later. These had employed another great up- 

 ward step, employing the wind to carry the pre- 

 cious package of heredity to another. Most of 

 the forest trees are of this class ; they do not vary 

 as do most other flowering trees and plants. 



The next step in advance in this direction was 

 when insects arrived and by cooperation began 

 carrying the heredity packages of pollen from 

 place to place, for which they received in return 

 a taste of honey. Now comes an era of most 

 astounding development. More than a hundred 

 and forty thousand species were brought into 

 existence and most annual plants and many 

 trees and shrubs and herbs now began, through 

 the selective influence of insects, to produce more 

 conspicuous and fragrant flowers and to secrett 

 honey just in the exact position to induce insects 



