HEREDITY 



505 



It is evident that, whatever the numbers involved, the above 

 is the proportion in which the pure and the mixed forms will 

 naturally appear in the first generation of admixture between 

 two pure forms. 



From this we see that indiscriminate breeding of distinct 

 characters results in both " pure " and " crossed," or mixed, 

 forms in their descendants, and this in the proportion of 1:2: i. 

 Now this is a short "frequency distribution," in which the 

 middle term represents the individuals of mixed breeding and is 

 equal to the sum of the two extremes. 



The second generation, or second remove from pure forms. 

 What now will be the character of the next generation, as bred 

 from the individuals B* (pure black), BR and BR (mixed), and 

 R* (pure red) ? 



Continuing the assumption of indiscriminate mating and uni- 

 form fertility, we shall have the following, remembering what 

 are the relative numbers involved, and that in the long rtin every 

 kind of female will mate with every kind of male, producing 

 offspring of the following character : 



CHARACTER OF OFFSPRING PRODUCED BY FEMALES OF DIFFERENT KINDS 

 WHEN MATING WITH MALES OF DIFFERENT KlNDS WITHOUT SELECTION 



This, then, expressed in its simplest form and the lowest 

 terms, is the population resulting from two generations of indis- 

 criminate breeding between forms originally pure. 



Two things are noticeable about this total. First, it has all 

 the characteristics of the ordinary frequency distribution (i, 

 4, 6, 4, i) ; and, second, it is a complete expression of the 



