Chap. IV.] NATUKAL SELECTION. 147 



they will have taken the places of, and thus exter- 

 minated, not only their parents (A) and (I), but likewise 

 some of the original species which were most nearly 

 related to their parents. Hence very few of the original 

 species will have transmitted offspring to the fourteen- 

 thousandth generation. We may suppose that only one, 

 (F), of the two species (E and F) which were least closely 

 related to the other nine original species, has transmitted 

 descendants to this late stas^e of descent. 



The new species in our 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 14 and z u will be much greater than that between 

 the most distinct 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 u , q u , £> 14 , will be nearly related 

 from having recently branched off from a 10 ; & 14 , and/ 14 , 

 from having diverged at an earlier period from a 5 , will 

 be in some degree distinct from the three first-named 

 species ; and lastly, o 14 , e 14 , and m 14 , will be nearly related 

 one to the other, but, from having diverged 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 a distinct genus. 



The six descendants from (I) will form two sub-genera 

 or genera. But as the original species (I) differed largely 

 from (A), standing nearly at the extreme end 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 sup- 

 posed to have gone on diverging in different directions. 



