1 8 EVOLUTIONS OF ORGANIZATION. 



factor in extinction' of species, but it was left for 

 Darwin to originate the idea that it could do what 

 Owen recognized as due to innate causes, viz., that 

 it could produce variety and advance by the con- 

 tinual survival in the contest of the " fittest," i. e. 

 of those which by accidental variations of structure 

 had in the struggle an advantage over their neigh- 

 bours. The struggle exists, beyond all question ; 

 and few can read Darwin's works without being 

 impressed with the likelihood of its resulting during 

 long periods in an indefinite amount of variety. 

 Yet, even as to this, it may be remarked that there 

 is a tacit assumption in the theory, that individuals 

 surviving by slight variations of different kinds 

 would be separated one from the other, so as not 

 to mix the different peculiarities to which they 

 severally owed their survival ; and it may be ob- 

 jected that such separation would be unlikely so 

 long as the variations were yet exceedingly slight ; 

 while it may be judged probable from Mr. Darwin's 

 own researches that individuals with slight consan- 

 guinity and differing minutely one from the other, 

 but not too greatly, would be exactly those which 

 would be most prolific and so give rise to a mixing 

 of incipiently diverging characters. 



The more important criticism can in no way be 

 eluded that the doctrine of natural selection has 



