158 THE EVOLUTION OF LIVING BEINGS. 



As long as the new forms, resulting from such inter- 

 crossing, do not transgress the border of the Linneon, 

 we can say, with justice, that such a Linneon maintains 

 itself by adaptation, although of course the adapted 

 Linneon is then internally changed e. g. is a group of 

 types of other constitutions, than the ones it previously 

 contained. 



In such a Linneon also, the struggle for life gradually 

 plays havoc because, by extermination of certain types, 

 it gradually reduces the scope of crossing and conse- 

 quently of adaptability. The struggle for life usually 

 results here, first in the selection of the dominant type 

 which can never proceed so far that pure dominants 

 only survive, because the hybrids with the dominant 

 characters enjoy the same advantages as the constitu- 

 tionally pure dominants in the struggle for life 



If therefore, the dominant form is selected, this is of 

 great advantage to such a Linneon, because then it 

 continues to contain the recessive forms — be it cry- 

 ptomerously — and consequently can call on them in 

 case of emergency. As however such a call is hampered 

 by the fact, that such recessives can come into being 

 only, if two impure dominants happen to mate, even 

 the selection of the dominants must in the long run 

 lead to extinction. Such extinction will however come 

 about much quicker, if the struggle for life results in the 

 selection of the recessives, because then the Linneon 

 finally becomes really mono-specific and so must 

 perish sooner or later, exactly like the self-fertilising 

 Linneons treated off above. 



