94 CHARLES DARWIN 



gives only 112 a margin of 139 doubtful forms of 

 shadowy indefiniteness. Varieties, in fact, are always 

 arising, and dominant species in particular always tend 

 to vary most in every direction. The reason why varia- 

 tion is not so marked in the wild state as under domes- 

 tication is of course because the conditions are there 

 less diverse ; but where the conditions of wild things 

 are most diverse, as in the case of dominant kinds, 

 which range over a wide space of country or of ocean, 

 abundant individual variations habitually occur. Local 

 varieties thus produced are regarded by Darwin as 

 incipient species : they are the raw material on which 

 natural selection gradually exerts itself in the struggle 

 for existence. 



Granting individual variability, then, how do species 

 arise in nature ? And how are all the exquisite adapta- 

 tions of part to whole, and of whole to environment, 

 gradually initiated, improved, and perfected ? 



Here Malthus and the struggle for life come in to 

 help us. 



For the world is perpetually over-populated. It is 

 not, as many good people fearfully imagine, on a half- 

 comprehension of the Malthusian principle, shortly 

 going to be over-populated; it is now, it has always 

 been, and it will always be, pressed close up to the 

 utmost possible limit of population. Reproduction is 

 everywhere and in all species for ever outrunning means 

 of subsistence; and starvation or competition is for 

 ever keeping down the number of the offspring to the 

 level of the average or normal supply of raw material. 

 A single red campion produces in a year three thousand 

 seeds ; but there are not this year three thousand times 



