248 LUTHER BURBANK 



members of the plant-insect union. The fact 

 that most of them retain more or less conspicuous 

 flowers proves this beyond question. In the case 

 of the wheat, which might be thought a possible 

 exception, there is the evidence of certain species 

 of wild wheat, growing to this day in Palestine, 

 which have only partially renounced allegiance 

 to the insects, still putting forth flowers that on 

 occasion may be cross-fertilized with their aid or 

 with that of the wind. 



Just why these various plants of different 

 families have departed from the custom that has 

 served their fellows so well, would be interesting 

 matter for conjecture. 



Yet that wheat should make this change is no 

 doubt because it has under cultivation been 

 grown en masse, giving it no opportunity for 

 individualization. The most plausible sugges- 

 tion is that the ancestors of the plants that now 

 have closed flowers and thus depend exclusively 

 upon self-fertilization had fallen upon evil days 

 in which there was a dearth of insect messengers 

 in the regions they inhabited. 



The story of the starved martins, told in an 

 earlier chapter, furnishes a striking illustration 

 of the fact that insects that ordinarily are abun- 

 dant may in any given season fail to make their 

 appearance. 



