232 Singing Valleys 



between two inbred parent lines produces a better corn than 

 either of the parents. A "double cross" between two hybrids, 

 in which four inbred parent lines contribute to the offspring, 

 is still better. A "three-way cross" between a hybrid and an 

 inbred variety with three family lines involved is not so 

 satisfactory as a "two-way cross." A "multiple cross," in which 

 eight families are inbred and brought together, is less reliable 

 than a "double cross." 



Shull first published his findings in 1908. Immediately the 

 creation of hybrid corns became the chief interest of corn- 

 makers in all the agricultural experiment stations. In this con- 

 nection it is interesting that previous to 1900 corn had been 

 self-fertilized very rarely by the experimenters. Indeed many 

 persons believed that corn was self-sterile. The World War 

 held back the development of hybrid corns while corn farmers 

 went in for mass production. But soon after 1920, hybrid corn 

 was put on the market for sale and immediately changed 

 corn-growing methods in this country. 



Says Merle T. Jenkins, principal agronomist of the Divisions 

 of Cereal Crops and Diseases of the U. S. Bureau of Plant 

 Industry, 



It is an outstanding example, perhaps the most outstanding 

 example, of the influence of theoretical scientific research in revolu- 

 tionizing the production practices of an agricultural crop. Although 

 it is a new development, the hybrids already produced have estab- 

 lished their superiority in productiveness and in resistence to wind, 

 disease and other unfavorable conditions. 



It is the peculiarity of hybrid corn that its value lies in the 

 first generation following the cross. It is like the mule, a supe- 

 rior animal in every respect except as regards its procreative 

 powers. The farmer who plants hybrid corn cannot save out 

 some of the crop to seed his fields the next spring; he must 

 buy new hybrid seed from the seed growers. True, the cost of 

 seed each year is more than made up by the extra large returns 

 per acre of hybrid corn. Meanwhile hybrid corn is building 



