36 THE GENESIS OF SPECIES. [CHAP. 



mentioning the frequent sudden appearances of domestic 

 varieties, he speaks of " the false belief as to the similarity 

 of natural species in this respect." 8 In his work on the 

 " Origin of Species," he also observes, " Natural Selection 

 acts only by the preservation and accumulation of small 

 inherited modifications." 3 And " Natural Selection, if it 

 be a true principle, will banish the belief ... of any great 

 and sudden modification in their structure." 4 Finally, he 

 adds, " If it could be demonstrated that any complex organ 

 existed, which could not possibly have been formed by nu- 

 merous, successive, slight modifications, my theory would 

 absolutely break down." ' 



Now the conservation of minute variations in many 

 instances is, of course, plain and intelligible enough; such 

 e. g., as those which tend to promote the destructive facul- 

 ties of beasts of prey on the one hand, or to facilitate the 

 flight or concealment of the animals pursued on the other ; 

 provided always that these minute beginnings are of such 

 a kind as really to have a certain efficiency, however small, 

 in favor of the conservation of the individual possessing 

 them ; and also provided that no unfavorable peculiarity 

 in any other direction accompanies and neutralizes, in the 

 struggle for life, the minute favorable variation. 



But some of the cases which have been brought for- 

 ward, and which have met with very general acceptance, 

 s.eem less satisfactory when carefully analyzed than they at 

 first appear to be. Among these we may mention " the 

 neck of the giraffe." 



At first sight it would seem as though a better exam- 

 ple in support of " Natural Selection " could hardly have 

 been chosen. Let the fact of the occurrence of occasional 

 severe droughts in the country which that animal has in- 



2 " Animals and Plants under Domestication," vol. ii., p. 414. 



3 "Origin of Species," 5th edit., 1869, p. 110. 



* Ibid., p. 111. 6 Ibid., p. 227. 



