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THE AMERICAN NATURALIST [Vol. XLV 



that size characters segregate. It is hoped that this evi- 

 dence will make us more cautious about accepting uncor- 

 roborated statements about characters which are definite 

 exceptions to the Law of Mendel. It is by no means 

 certain that no such exist, but no experimental proof of 

 hybrids non-Mendelian in character has been made. 



A further proof of segregation of size characters has 

 recently been made in a preliminary note by Emerson. 10 

 He states that definite segregation occurs in beans, 

 gourds, squashes and maize. His full data are therefore 

 awaited with great interest. 



Table I shows the frequency distribution of the heights 

 of plants in a cross between no. 5 a medium-sized flint 

 maize and no. 6 a tall dent maize. Sufficient seed was 

 obtained in a previous season so that the entire series 

 could be grown in rows side by side during one summer. 

 This procedure eliminates any possibility that the varia- 

 bility of the F 2 generation might have come from varying 

 conditions of soil fertility. 



It will be noticed that the Fj generation is nearly as tall 

 as the taller parent. This increase in size is not due to 

 dominance. It is the increased vigor that comes from 

 crossing in maize, and while it obscures the hereditary 

 differences in size, it is really a problem of development 

 and not of heredity as was shown in a previous paper. 11 



The distribution of heights in the F 2 generation is seen 

 by simple inspection of the table to be more variable than 

 the F x 'generation in the. case of each ear planted. Re- 

 duced to simple terms by the calculation of the coefficient 

 of variation in each case, however, the two generations 

 can be compared more accurately. In the F, generation 

 the C.V. = 8.68 ±.553 while in the various F 2 genera- 

 tions from different ears the coefficients of variation run 

 from 12.02 ± .559 to 15.75 ± .684. 



10 Emerson, R. A., 1910, "Inheritance of Sizes and Shapes in Plants," 

 Amer. Nat., 44: 739-746. 



11 East, E. M., 1909, "The Distinction between Development and Hered- 



