A NEW ZEBRA HYBRID. 107 



(2) The decrease in size and vigor which accompanies self- 

 fertilization is greatest in the first generation, and becomes less and 

 less in each succeeding generation until a condition is reached in 

 which there is (presumably) no more loss of vigor. 



(3) Self-fertilized families from a common origin differ from 

 one another in definite hereditary morphological characters. 



(4) Regression of fluctuating characters has been observed to 

 take place away from the common mean or average of the several 

 families instead of toward it. 



(5) A cross between sibs? within a self- fertilized family shows 

 little or no improvement over self-fertilization in the same family. 



(6) A cross between plants belonging to two self-fertilized 

 families results in a progeny of as great vigor, size, and productive- 

 ness, as are possessed by families which had never been self-fertilized. 



(7) The reciprocal crosses between two distinct self-fertilized 

 families are equal, and possess the characters of the original corn with 

 which the experiments were started. 



(8) The F x from a combination of plants belonging to certain 

 self-fertilized families produces a yield superior to that of the original 

 cross-bred stock. 



(9) The yield and the quality of the crop produced are func- 

 tions of the particular combination of self-fertilized parental types, 

 and these qualities remain the same whenever the cross is repeated. 



(10) The F x hybrids are no more variable than the pure strains 

 which enter into them. 



(11) The F 2 shows much greater variation than the Fj. 



(12) The yield per acre of the F 2 is less than that of the F x . 



[Presented by Committee on Breeding Corn.] 



