father, and vice versa. For this reason the deterioration which 

 comes from close inbreeding coupled with cross-fertilization should 

 not be as rapid though just as sure as by self-fertilization. This 

 again is in accord with such observations as are on record. 



As most of the important characteristics for which the corn 

 breeder strives are closely related to the question of physiological 

 vigor the fundamental problem in breeding this plant is the devel- 

 opment and maintenance of that hybrid combination which pos- 

 sesses the greatest vigor. Up to a certain point the common em- 

 pirical method of selection will mostly eliminate only those com- 

 ponents which do not contribute to the best possible result, and 

 the more rigid the selection during this period the more rapid will 

 be the improvement of the selected strain; but if the selection is 

 continued in the same rigid manner after these inferior components 

 are eliminated, it may lead to the loss of one after another of the 

 component biotypes which had added to the physiological vigor 

 of the strain and there will then be a resultant deterioration, es- 

 pecially if among the characteristics which guide the selection 

 are some which are unrelated to vigorous growth. The funda- 

 mental defect in every empirical scheme of corn-breeding which 

 simulates the isolation methods of the breeder of small grains, 

 lies in the fact that there is no intelligent attempt in these methods 

 to determine the relative value of the several biotypes in hybrid 

 combination, but only in the pure state. 



In the present state of our knowledge it is impossible to predict 

 from a study of two pure strains what will be the relative vigor 

 of their hybrid offspring. That is an important relation which future 

 investigations must unlock for us. The problern of getting the 

 seed-corn that shall produce the record crop, or which shall have 

 any specific desirable characteristic combined with the greatest 

 vigor, may possibly find a solution, at least in certain cases, similar 

 to that reached by Mr. O. I. Simpson in the breeding of hogs by 

 the combination of two strains which are only at the highest quality 

 in the first generation, thus making it necessary to go back each 

 year to the original combination, instead of selecting from among 

 the hybrid offspring the stock for continued breeding. That is, 

 it may be found that the desirable combination of elementary 

 species of Indian corn will be best attained by separating and re- 

 combining in some definite manner the different elementary species, 

 or on the other hand it may be found that selection according to 

 the empirical methods now most approved can be carried to a point 

 at which the most efficient combination has been isolated from the 

 less efficient components and may then be maintained only by a 

 relaxation of the rigid selection. 



Such questions as these cannot be settled in the study, but only 

 in the field by means of carefully conducted experimentation. 

 I hope that those experiment stations which are dealing with the 

 problems of the improvement of maize will undertake the solution 



