248 LUTHER BURBANK 



members of the plant-insect union, i « t 



that most of them retain more or less conspicuous 

 flowers proves this beyond question. In the case 

 of the wheat, which miffht be thought a possible 

 exception, there is the evidence of cfHain species 

 of wild wheat, lowing to this da i ' ilestine, 



which have only partially renounced allefl^ancr 

 to the insects, still putting forth flowers that on 

 occasimi may be crcws-fcrtilizrd with thrir alH or 

 with that of the wind. 



Just why these various plant > "f <liffcrent 

 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 diange is no 

 doubt because it has under cultivation been 

 grown en nuuie, 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. 



