416 PEACTICAL BOTANY 



several of the best plants in each hundred-group are reserved 

 for seed. The total produced by each hundred-group is weighed 

 to enable the experimenter to estimate the comparative value 

 of the mother plants of (1). 



(3) The third year the process of the second year is repeated. 



(4) The fourth year the same process is repeated. 



(5) The fifth year the most promising varieties are planted 

 in small fields in the ordinary way. Those varieties which yield 

 abundantly in the field and turn out well in the milling tests 

 applied to the harvested grain are distributed among farmers 

 for seed wheat. 



A new variety can soon be introduced over an immense 

 territory. It is estimated that in fifteen years from the time 

 of planting one seed, its descendants might be made to cover 

 more than 5,000,000 acres of wheat fields. 



Wheat breeding is still making such rapid progress that it 

 is not now possible to say how much the quality and quantity 

 of our wheat crop may yet be improved by the introduction 

 of better varieties. The total number of acres in the United 

 States differs considerably from year to year. It seems likely, 

 as a rule, to exceed 45,000,000 acres. ^ The average yield 

 ranges between 10 and 15 bushels per acre, although it is 

 possible with the most improved seed on the best soils to 

 raise more than 40 bushels per acre.^ Clioice of the best seed 

 would undoubtedly increase the average yield to from 13 to 

 at least 18 bushels. It is easy to see how important a gain 

 this would be if it were calculated in terms of the current 

 price of wheat. 



383. Principles upon which wheat breeding depends.^ The 

 work of Le Oouteur and of a Scotch breeder of small grams 

 named Patrick Shirreff, who discovered his first valuable 



1 See Carleton, "The Future "Wheat Supply of the United States," 

 Science, August 5, 1910. 



2 See Hopkins, Soil Fertility and Permanent Agriculture. Ginn and 

 Company, Boston. 



8 See De Vries, Plant Breeding. Open Court Publishing Co., Chicago. 



