10 LUTHER BURBANK 



you will find that you must pull open the little 

 bracts in which the flowers are incased, in order 

 to make the stamens and pistils visible. Under 

 ordinary circumstances, insects cannot find access 

 to them. The wind has no influence over them. 

 Their normal habit is to fertilize the pistil of each 

 individual flower with pollen from the stamens 

 that grow within the same closed receptacle. 



This is inbreeding of the closest and most in- 

 timate character, and there is obviously no gen- 

 eral opportunity to introduce the element of vari- 

 ability which, as we have seen illustrated over and 

 over, cross- fertilization brings. 



So the essential qualities that make wheat val- 

 uable have been aggregated in a few fixed com- 

 binations, and the resulting varieties of wheat, 

 differing not very widely from one another, are 

 rarely crossed, unless by artificial means to meet 

 the special needs of the plant developer. 



They remain fixed because they are of pure 

 lineage. 



MIXED ANCESTRY AND INBREEDING 



The case of the wheat is typical. Its develop- 

 ment furnishes an illustration of the method 

 through which many specialized races of animals 

 and plants under domestication have been devel- 

 oped. Indeed, it might almost be said that the 



