Darwin s Artificial and Natural Selection 123 



shows that if a single individual were born, which varied in 

 some manner, giving it twice as good a chance of life as that 

 of the other individuals, yet the chances would be strongly 

 against its survival. Supposing it to survive and to breed, 

 and that half its young inherited the favourable variation ; 

 still, as the reviewer goes on to show, the young would have 

 only a slightly better chance of surviving and breeding ; and 

 this chance would go on decreasing in the succeeding genera- 

 tions. The justice of these remarks cannot, I think, be dis- 

 puted. If, for instance, a bird of some kind could procure 

 its food 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 ex- 

 clusion of the common form ; but there can hardly be a 

 doubt, judging by what we see taking place under domestica- 

 tion, that this result would follow from the preservation dur- 

 ing 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." 



There then follows what, I believe, is one of the most sig- 

 nificant admissions in the " Origin of Species " : — 



" 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 numer- 

 ous instances could be given with our domestic productions. 

 In such cases, if the varying individual did not actually trans- 

 mit to its offspring its newly acquired character, it would 

 undoubtedly transmit to them, as long as the existing condi- 

 tions remained 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 been 

 similarly modified without the aid of any form of selection. 



