f40 THE DOCTRINE OF DESCENT. 



that doubtful species are not exceptional, as the old 

 school was wont to imagine, but that it is merely owing 

 to an inadequate knowledge of the material out of which 

 species are constructed, that all species are not looked 

 upon as doubtful and artificial. 



Let us here again call to mind that in many thou- 

 sand cases the most rigid systematizers are unable 

 to state where their species begin and end ; of which 

 Darwin, as an instance, cites a communication by 

 H. C. Watson, that 182 British plants, usually regarded 

 as varieties, have each been claimed as independent 

 species by individual botanists."^ Darwin's immortal 

 service consists in having shown what is the power 

 which operates upon the existing variable individuals 

 and species, and what results this operation must pro- 

 duce. He found the key in the word which has become 

 a badge and common property of our age, " the struggle 

 for life,"* and has thus given the foundation and theory 

 of a doctrine of which the truth had long before been 

 manifest to an intellect such as that of Lamarck. He 

 founded the doctrine of Descent on the theory of selec- 

 tion, when he proved that in nature the struggle for 

 existence occasions a selection of the best and fittest, 

 comparable to artificial breeding, and giving rise to new 

 races and new species. 



The struggle for life, this helium onuiiuin contra 

 omnes^ is, moreover, an undisputed and undeniable fact, 

 which we here accept in its widest relations. Not only 

 does the beast of prey war against the graminivorous 

 animals, which again strive to keep their balance hy 

 superior multiplication, speed, and cunning; the gradual 



* For Wallace's share in this honour, see the end of this chapter. 



