CONFORMITY TO TYPE 246 



whiteness may be present and completely concealed by 

 blackness. Mendel's tabulation of what happens when 

 only two sets of characters are concerned is shown thus: 



A. Dominant character; a, recessive character; Aa, 

 hybrid. For brevity's sake it is assumed that each 

 plant produces only four seeds (peas). 



Generation A A a a Ratio 



A Aa : a 



1 1 2 1 12:1 



2 6 4 6 32:3 



3 - 28 8 28 72:7 



4 120 16 120 15 2 : 15 



5 496 32 496 31 2 :31 



In the tenth generation, therefore, 2 n 1 = 1023. In 

 each 2,048 plants that arise in this generation 1,023 will 

 show constant dominant character, 1,023 will show 

 constant recessive character, and only two will be hybrids. 



Thus, there is a spontaneous tendency to escape from 

 hybridity, taking place under the most favorable condi- 

 tions with a regularity susceptible of mathematical 

 calculation and of formulation as a law. 



Spillman expresses the Mendelian law thus : " In the 

 second and later generations of a hybrid, every possible 

 combination of the parent character occurs, and each 

 combination appears in a definite portion of the indi- 

 viduals." With more technical diction Lock defines it 

 thus: "The gametes of a heterozygote bear the pure 

 parental allelomorphs completely separated from one 

 another, and the numerical distribution of the separate 

 allelomorphs in the gametes is such that all possible 

 combinations of them are present in approximately 

 equal numbers. " . . . " The male and female germ cells 

 of hybrid plants contain each of them one or the other 

 member only of any pair of differentiating characters 



