1 (30 Vererbung, Variation, Mutation. 



The results in crossing Berkshire and^ Yorkshire breed of swine and the 

 Poland China and Yorkshire breeds show complete dominance of the Yorkshiren 

 white over the Berkshire or Poland China black in the F l generation. There 

 was a general tendency for the original parent colors to be expressed separately 

 and in the proportion of 3 dominants to 1 recessive, in the individuals of the 

 F 2 generation. In nearly all eases the extracted recessive blacks of the F. 2 ge- 

 neration carried more white than the original black parents. This suggests that 

 a number of germinal factors are concerned in the production of each color rather 

 than a single factor. "Although the factors may behave as a unit or Single factor 

 when mated with individuals carrying like factors, when crossed, the unity is 

 destroyed and independent behavior on the part of some of the factors is the 

 possible result." Pearl. 



390) EmersOli, R. A., The Inheritance of a Recurring Somatic Varia- 

 tion in Variegated Ears of Maize. In: Nebraska Agr.Expt. Sta. Bull. No. 4, 

 S.5— 34, Feb. 1914. 



In this paper the author shows that a somatic Variation in maize is inheri- 

 ted in simple Mendelian fashion. The Variation has to do with the development 

 of a dark red pigment (or in one stock a brown pigment) in the pericarp of the 

 grains, often associated with the development of an apparently similar pigment 

 in the cob and husks. Plants in which this pigment has a variegated pattern may 

 show any amount of red pericarp. The amount of pigment developed in the peri- 

 carp of variegated seeds bears a defmite relation to the development of color in 

 the progeny of such seeds. Experimental results indicate that the more color in 

 the pericarp of the seeds planted the more likely are they to produce plants 

 with wholly seif red ears, and, correspondingly, the less likely to yield plants 

 with variegated ears. Self-red ears thus produced are shown to behave in inheri- 

 tance as if they were hybrids between self-red and variegated races or between 

 self-red and non-red races, the behavior in any given case depending upon 

 whether the parent variegated ears were homozygous or heterozygousfor varie- 

 gated pericarp and whether they were self-pollinated or crossed with white. 



It is suggested that these results may be interpreted by the assumption that 

 a genetic factor for variegation, V, is changed to a self-color factor, S, in a somatic 

 cell. All pericarp cells directly descended from this modified cell will, it is assu- 

 med, develop color, and of the gametes arising from such modified cells one half 

 will carry the S factor and one half the V factor if only one of the two V fac- 

 tors of the somatic cells is changed, or all such gametes will carry S if both V 

 factors are changed. The V factor is thought of as a sort of temporary, reces- 

 sive inhibitor that sooner or later permanently loses its power to inhibit color 

 development, becoming thereby an S factor. Or it may be that the dominant 

 factor, S, is temporarily inactive, but sooner or later becomes permanently active. 

 Again, the S factor may repeatedly arise de novo. The cause of any such change 

 in factors is beyond intelligent discussion at present. The results of Correns with 

 Mirabilis and of de Vries with Antirrhinum are shown to be subject to the same 

 analysis as that used to interpret the results secured with maize. Pearl. 



