94 Results of the Action of Chap. iv. 



quite new station, in which offspring and progenitor do not come 

 into competition, both may continue to exist. 



If, then, our diagram be assumed to represent a considerable 

 amount of modification, species (A) and all the earlier varieties will 

 have become extinct, being replaced by eight new species (a 14 to 

 m 14 ) ; and species (I) will be replaced by six (n u to z u ) new species. 



But we may go further than this. The original species of our 

 genus were supposed to resemble each other in unequal degrees, as 

 is so generally the case in nature ; species (A) being more nearly 

 related to B, C, and D, than to the other species ; and species (I) 

 more to G, H, K, L, than to the others. These two species (A) and 

 (I) were also supposed to be very common and widely diffused 

 species, so that they must originally have had some advantage over 

 most of the other species of the genus. Their modified descendants, 

 fourteen in number at the fourteen-thousandth generation, will 

 probably have inherited some of the same advantages : they have 

 also been modified and improved in a diversified manner at each 

 stage of descent, so as to have become adapted to many related 

 places in the natural economy of their country. It seems, therefore, 

 extremely probable that they will have taken the places of, and 

 thus exterminated, 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 trans- 

 mitted 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 trans- 

 mitted descendants to this late stage of descent. 



The new species in our diagram descended from the original 

 eleven species, will now be fifteen in number. Owing to the diver- 

 gent tendency of natural selection, the extreme amount of difference 

 in character between species a u and z li 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 dif- 

 ferent manner. Of the eight descendants from (A) the three marked 

 a 14 , q u , p 14 , will be nearly related from having recently branched off 

 from a 10 ; b 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 





