THE THEORY OF NATURAL SELECTION. 285 



of animals. If we suppose, namely, that the giraffe, to 

 begin with, possessed a neck of no more than normal 

 length, and lived principally upon the ordinary terrestrial 

 herbage ; and if we further suppose a severe and pro- 

 tracted drought to occur in the region inhabited by 

 the giraffes, we may assume that many individuals would 

 perish for want of food, but that some would manage 

 to survive. In all such cases there must be some general 

 reason to account for the survival of the few who did 

 survive, in preference to the many who perished. In 

 this particular instance we may suppose that the indi- 

 viduals who survived were those who possessed necks 

 of a slightly greater length than the average, and who, 

 therefore, were better fitted for browsing upon shrubs 

 or trees, after the herbage had been destroyed by the 

 drought, than were the more normal individuals. This 

 imaginary example, then, will show how the possession 

 of a favourable variation tends to preserve certain 

 individuals, in preference to those which are without 

 the variation. 



(5) But, the young of all animals and plants tend 

 to inherit the peculiarities of their parents. Hence, 

 favourable variations or peculiarities which preserve alive 

 certain individuals of each species, will tend to be handed 

 down to their offspring. On the other hand, individuals 

 not possessing these favourable variations, or possessing 

 unfavourable variations, are killed off, and do not have 

 the opportunity of transmitting their peculiarities to off- 

 spring. The general action of the law of the ' Survival of 

 the Fittest,' or of ' Natural Selection,' is, thus, to preserve 

 all favourable variations which may occur among the indi- 



