THE IMPORTANCE OF BROAD BREEDING IN CORN. 43 
shown by the sterility of self-pollinated plants, has been unheeded, 
largely because theories and methods have been carried over to corn 
from other crops which are normally self-pollinated or where a high 
degree of uniformity is essential. 
Great uniformity is of little or no economic value in corn varieties, 
and since it can be acquired only through close breeding it is actually 
undesirable to the grower. The natural requirements of cross-pollina- 
tion make the problem of corn improvement entirely different from 
that of most of our cultivated plants. 
Selection for increased yield with the maximum instead of the 
minimum of cross-breeding seems never to have been tried as a scien- 
tific experiment. On the other hand, the farmers of our corn-grow- 
ing regions have practiced a system of broad breeding by choosing 
many ears from widely scattered plants in large fields and mixing the 
shelled corn,before planting. Much of the basic improvement of our 
corn varieties may be ascribed to this system of increasing and main- 
taining vigor and fertility. 
An effort to reduce the intimate intuitive knowledge of the successful 
breeder to measurable characters has led to the development of the score 
card. Instead of accomplishing the desired result, the score card 
has operated to intensify the closeness of selection, since uniformity 
in formal characters can be secured only by close breeding. 
Although the methods that obtain among the primitive tribes of 
corn-growing Indians indicate that corn has been subjected to narrow 
breeding from remote times, the more intensive form of narrow 
breeding has been practiced for little more than a decade, yet the 
debilitating effects of this method are becoming apparent. 
That corn is benefited by additional crossing, even when grown. by 
primitive methods, is indicated by the custom which some tribes 
have of regularly mixing distinct strains to increase the yield. 
It is abundantly demonstrated that the crossing of distinct varieties © 
gives increased yields.* With the idea that only uniform varieties 
could be of value the practical importance of this fact has been over- 
looked and the gain has been limited by subsequent inbreeding of the 
“After this report was submitted in January, 1909, an article appeared by Dr. 
E. M. East, of the Connecticut Agricultural Experiment Station (see American 
Naturalist for March, 1909), describing additional instances of increased yields 
of corn hybrids. Thirty different crosses between varieties were grown in 
comparison with the parent varieties, with the result that “In every case an 
increase in vigor over the parents was shown by the crosses.” In the four 
cases in which the yields were measured the product of the hybrid exceeded 
that of either parent, the increase of the hybrids over the parents averaging 
77 per cent. Doctor East also considers the practicability of producing hybrid 
seed for commercial plantings and outlines a method practically identical with 
that suggested here. 
141—-1V 
