‘ 
DIVERGENT EVOLUTION THROUGH SEGREGATION, cay) 
Third. A similar distinction is found when we compare the right- 
hand column with the left-hand column. The smallest term in the for- 
mer is to the largest term in the same column as 1 to 899, while in the 
left-hand column the greatest difference is as 1 to 100. This shows that 
when segregate fecundity is strongly developed, differences in the de- 
grees of segregation produce greater contrasts than the same differ- 
ences produce when the segregate fecundity is but slightly developed. 
Fourth. Once more let us consider the relations to each other of 
the four terms that stand in the upper left-hand corner of the table. 
Suppose that of some one variety of a plant species, characterized by 
pre-potential segregation and segregate fecundity, we have occurring in 
equal numbers four variations whose relations to other varieties are 
indicated by the figures given in these four terms, while in their rela- 
tions to each other they are completely fertile and not segregated. 
Which variation will leave the greatest number of pure offspring; that 
is, the greatest number of offspring belonging to the one variety to 
which the four variations alike belong? Evidently the variations rep- 
resented by the fraction ;§; will have the greatest influence on the fol- 
lowing generation. But as the supposed conditions allow of exact 
computation, let us look at the problem a little closer. If each varia- 
tion numbers say a thousand individuals, then the number of each that 
will breed true will be as follows: Of the one represented by— 
75, 526 will breed true and 474 will cross, 
yy, 550 will breed true and 450 will cross, 
“85, 555.5 will breed true and 444.5 will cross, 
+5, 600 will breed trne and 400 will cross. 
And the next generation of each kind will be as follows: Multiplying 
the pure parents by 10, and the hybrid parents by 8 or 9, according to 
the value of m, we have those represented by— 
yo, pure offspring 5260, hybrids 4266, 
7, pure offspring 5500, hybrids 4050, 
3, pure offspring 5555, hybrids 3556, 
35, pure offspring 6000, hybrids 3200. 
There can therefore be no doubt that under such conditions the aver- 
age pre-potential segregation and segregate fecundity of the next gen- 
eration wlll be considerably advanced, and so with each successive 
generation till the average of the pure forms is represented by the 
fraction 5§;, and is surrounded by a cirele of variations, of which one 
will be represented by the fraction ~;. And from this new point con- 
tinuous advance will be made toward ever higher and higher grades 
of segregation and segregate fecundity; though of course the process 
will be subject to antagonisms and limitations arising from the princi- 
ples of self-accumulating vigor and self-accumulating adaptation. Let 
it however be carefully noted that we have in this process the mani- 
festation of a new principle, for it rests not only on self-accumulating 
positive segregation, but on self-accumulating segregate fecundity. 
