Chap. IV. 
DIVERGEKCE OF CHAKACTER. 
123 
The new species in onr diagram descended from the 
original eleven species, will now be fifteen in number. 
Owing to the divergent tendency of natural selection, 
the extreme amount of difference in character between 
species a and z will be much greater than that be¬ 
tween the most different of the original eleven species. 
The new species, moreover, will be allied to each other 
in a widely different manner. Of the eight descendants 
from (A) the three marked a q p will be nearly 
related from having recently branched off from a 
and / from having diverged at an earlier period from 
a^, will be in some degree distinct from the three first- 
named species; and lastly, o e and m will be 
nearly related one to the other, but from having di¬ 
verged at the first commencement of the process of 
modification, will be widely different from the other 
five species, and may constitute a sub-genus or even a 
distinct genus. 
The six descendants from (I) will form two sub¬ 
genera or even genera. But as the original species (I) 
differed largely from ( A), standing nearly at the extreme 
points of the original genus, the six descendants from 
(I) will, owing to inheritance alone, differ considerably 
from the eight descendants from (A) ; the two groups, 
moreover, are supposed to have gone on diverging in dif¬ 
ferent directions. The intermediate species, also (and 
this is a very important consideration), which connected 
the original species (A) and (I), have all become, ex¬ 
cepting (F), extinct, and have left no descendants. 
Hence the six new species descended from (I), and the 
eight descended from (A), will have to be ranked as 
very distinct genera, or even as distinct sub-families. 
Thus it is, as I believe, that two or more genera 
are produced by descent with modification, from two 
or more species of the same genus. And the two or’ 
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