64 CROSSBREEDING CORN. 



As seasonal differences have a marked effect upon the comparative 

 production of varieties the success of a cross one season may be found 

 fleeting if continued. 



The fact that the variety Tindal in its adverse performance toward 

 crossing has rather emphatically ignored all the influences of rank and 

 adaptation that seem to govern other varieties may indicate that 

 advantageous exceptions may also be found; but whatever further 

 investigation may demonstrate, present knowledge indicates that the 

 economic increasing of corn yields by means of crossing is attended 

 with many complexities. 



GENERAL CONSIDERATION OF ALL THE TESTS. 

 INDICATIONS OF INTERMEDIACY. 



As the varieties crossbred at the various points are varieties that 

 have met with general favor as grain producers, the characters of the 

 male and female parents of each cross are not radically different, and 

 consequently any intermediacy of a cross is not as apparent as it 

 might be if the parents were much unlike. However, in many 

 instances intermediacy between the two parents was observed regard- 

 ing various characters; such as productiveness, height of stalk, length 

 of growing season, and percentage of moisture. 



Averages of many crosses usually indicate intermediacy, because 

 exceptions in one direction from the median points are offset by 

 exceptions in the other direction, but under the conditions of these 

 and other tests of this nature so few instances have been shown in 

 which the first-generation crosses produced less than the average of 

 the two parents as to indicate that the average productiveness of 

 first-generation corn crosses is usually above the average of the 

 parents. It may be that this indication ^\^ll not be found entirely 

 due to advantages regarding adaptation, age of seed, self-fertilization, 

 etc., that most of the reported tests ^ have given to the first-generation 



1 Beal, W. J. Reports, Michigan Board of Agriculture, 1876, 1877, 1S81, and 1882. 



Ingersoll, C. L. Seventh and Ninth Annual Reports of Purdue University, 1881 and 1883. 



Sanborn, J. W. Indian Com. Agriculture of Maine, Thirty-third Annual Report, Maine Board of AgrL 

 culture, 1889-90. 



Kellerman, W. A., and Swingle, W. T. Crossed Varieties of Corn. Bulletin 17, Kansas Agricultural 

 Experiment Station, 1890. 



McCluer, G. W. Com Crossing. Bulletin 21, Illinois Agricultural Experiment Station, 1892. 



Morrow, G. E., and Gardner, F. D. Bulletins 25 and 31, Illinois .Vgricultural Experiment Station, 1893 

 and 1S94. 



Webber, H. J., and Swingle, W. T. Hybrids and their Utilization in riant Breeding. Yearbook, 

 U. S. Dept. of Agriculture, for 1897. 



Vanattor, Phares O. Annual Report, ^■i^ginia Agricultural Experiment Station, 1906. 



ShuU, G. H. The Composition of a Field of Com. Report, American Breeders' Association, vol. 4, 1908 

 Also A Pure Line Method in Com Breeding. Report, same, vol. 5, 1909. 



East, E. M. The Distinction between Development and Heredity In Inbreeding. American Natu- 

 ralist, vol. 43, No. 507, 1909. 



Collins, G. N. The Value of First-Generation Hybrids in Com. Bulletin 191, Bureau of Plant Industry, 

 U. S. Dept. of Agriculture, 19in. Increased yields of Corn from Hybrid Seed. Yearbook, U. S. Dept. of 

 Agriculture, for 1910. 



Hays, II. K., and East, E. M. Improvement in Corn. Bulletin 168, Conneoticut Agrlcultiiral 

 Experiment Station, 1911. 



218 



