136 THE ORIGIN OF SPECIES 



more easily by having its beak curved, and if one were 

 born with its beak strongly curved, and which conse- 

 quently flourished, nevertheless there would be a very 

 poor chance of this one individual perpetuating its kind 

 to the exclusion of the common form; but there can 

 hardly be a doubt, judging by what we see taking place 

 under domestication, that this result would follow from 

 the preservation during many generations of a large 

 number of individuals with more or less strongly curved 

 beaks, and from the destruction of a still larger number 

 with the straightest beaks. 



It should not, however, be overlooked that certain 

 rather strongly marked variations, which no one would 

 rank as mere individual differences, frequently recur 

 owing to a similar organization being similarly acted 

 on — of which fact numerous instances could be given 

 with our domestic productions. In such cases, if the 

 varying individual did not actually transmit to its ofiE- 

 spring its newly-acquired character, it would undoubtedly 

 transmit to them, as long as the existing conditions re- 

 mained the same, a still stronger tendency to vary in the 

 same manner. There can also be little doubt that the 

 tendency to vary in the same manner has often been so 

 strong that all the individuals of the same species have 



1 been similarly modified without the aid of any form of 

 selection. Or only a third, fifth, or tenth part of the 

 individuals may have been thus affected, of which fact 



S^several instances could be given. Thus Graba estimates 

 that about one-fifth of the guillemots in the Faroe Islands 

 consist of a variety so well marked that it was formerly 

 ranked as a distinct species under the name of Uria lac- 

 rymans. In cases of this kind, if the variation were oi 



