lis RESULTS OF THE ACTION OF Chap. IV. 



will generally tend to l^ecome extinct. So it probably Avill 

 be ^vith many -whole collateral lines of descent, Avhich ^vill be 

 conquered by later and improved lines of descent. If, liow- 

 ever, the modified offspring of a species get into some distinct 

 country, or become quickly adapted to some cjuite new station, 

 in whic-h offspring and progenitor do not come into compe- 

 tition, both may continue to exist. 



If, then, our diagram be assumed to represent a consider- 

 able amount of modification, species (A) and all the earlier va- 

 rieties Avill have become extinct, having" been replaced by eight 

 new species (a" to wi") ; and (I) will have been replaced 

 by six (?i" to 2'*) new species. 



But we may go further than this. The original species 

 of our genus were supposed to resemble eacli 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-dilfuscd 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 exterminatod, 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- 

 tliousandth generation. AVe 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 stage of descent. 



The new species in our diagram, descended from the origi- 

 nal eleven species, will now be lifteen in number. Owing to 

 the divergent tendency of natural selection, the extreme 

 amoimt of difference in character betAveen species «'* and 2'* 

 will be much greater than that between the most distinct of 

 the original eleven species. The new species, moreover, wiK 

 be allied to each other in a Avidely-differcnt manner. Of the 

 eight descendants from (A) the three marked a", <j^\ p^\ will 



