THE EVOLUTION OF LIVING BEINGS. 87 



change in the conditions to which it is itself adapted 

 or, if one prefers, resistant, takes place. While thus 

 extermination of dominants may lead, by the narrowing 

 down of the Linneon to a single recessive species, to 

 its extinction, elimination of the recessives never leads 

 to their total extinction, because these recesives 

 survive cryptomerously in the gametes of those hy- 

 brids which are indistinctible from the dominants, 

 and therefore share all protection which the latter 

 may enjoy. 



The idea that the aberrant types the recessives 

 are varieties of the most common type the do- 

 minant one is consequently a mistake ; the aberrant 

 forms never arose from the dominant one, but are se- 

 gregates from the hybrids indistinctible from the do- 

 minant type. Hereditable variability 

 spells segregation. 



The Linneon : Lepus cuniculus, consequently is not 

 a unit but a group of different types and their hybrids. 



That this is really the case would be difficult to pro- 

 ve in the case of the wild rabbit, because we can get 

 this proof only by mating two hybrid grey forms and, as 

 these are indistinctible from the pure dominants, a 

 very large number of matings would be required to 

 find a pair of such hybrids. 



If we disposed of a sufficiently large number of 

 pure black wild rabbits, it would however be compara- 

 tively easy to get the impure grey males because a grey 

 male mated with such a black, giving grey children 

 only, would be pure ; a grey male mated with such a 

 black (preferably with the same), giving a mixture of 



