290 LUTHER BURBANK 



have the seeds masqueraded that many farmers, 

 thinking their seed was thoroughly clean, later 

 found this weed and have believed that the seeds 

 changed into wheat, barley, oats, or whatever the 

 grain happened to be. 



This mimicry, of course, is developed by evolu- 

 tion. That is, those seeds which are most nearly 

 like the seeds with which they are mixed are over- 

 looked in cleaning and remain to perpetuate the 

 race. After many generations of this sort of 

 natural selection, the seeds constantly tend to 

 approach the grain seed in form, size, weight, 

 and color. 



Seeds do not change their botanical characters 

 as farmers sometimes suppose, but, having a 

 hard coat, may lie in the ground until a wet 

 season when the grain is destroyed and the weed 

 takes its place. 



Many States have long maintained official seed 

 inspection for purity. Now there is a United 

 States law of similar nature. These laws have 

 been so well enforced that there is not so much 

 danger now of infesting land with weed seeds as 

 was the case a few years ago. 



Farmers who make a practice of bilying grain 

 for seed from their neighbors or other persons 

 who have not had their seeds examined by in- 

 spectors are likely to have their fields infested 



