and the Darwinian Theory. J (31 



tations from being interfused. In the second place, as lono- 

 as we follow Darwin's explanation of the causes of natural 

 selection, we must hold that the representatives of one species 

 while surrounded by the same environment, whether prevented 

 from intercrossing or not, will, through the uniform action of 

 natural selection, be modified in the same way, if at all, and 

 while surrounded by distinct and dissimilar environments, 

 will be modified in divergent ways ; but in this latter case, as 

 they will be prevented from competing with each other by 

 occupying different areas, they can derive no advantage from 

 divergence of character through its preventing competition; 

 therefore the divergence that follows must be attributed to 

 some other cause. In other words, the advantage attributed 

 by Darwin to divergence of character is freedom from com- 

 petition, through diversity of adaptation, and, as some degree 

 of prevention of crossing is necessary for permanent difference 

 in adaptations, the advantage cannot be secured unless there 

 is some cause preventing the crossing of the divergent forms. 

 Now the prevention of crossing, if it ever arises, will be 

 secured either while the individuals that are prevented from 

 interbreeding are occupying the same limited area and exposed 

 to the same environment, or while occupying distinct areas 

 and exposed to either the same or different environments. 

 In the first case we are told by Darwin that exposure to uni- 

 form conditions " will tend to modify all the varying indi- 

 viduals of the same species in the same manner." in the 

 second case, as the sections of the species that are prevented 

 from crossing occupy separate areas, the advantage of freedom 

 from competition is already secured without divergent adap- 

 tation, and there can be no further advantage of that kind. 



Again, it is not difficult to show that divergence is in itself 

 no benefit, for multitudes of more divergent forms fail, leaving 

 the field to less divergent ones. This is generally true of 

 monstrosities and frequently true of other kinds of variations. 

 Neither can it be claimed that freedom from competition is 

 an advantage, unless it results in freer access to unappropria- 

 ted resources, and this advantage is most frequently gained by 

 migrating into a locality presenting the same environment, 

 but not previously occupied by the species. In this last case 

 the access to unappropriated resources does not depend on 

 new adaptations ; and, as any new adaptations that might 

 bring advantage to the representatives of the species in one 

 district would be of equal advantage in the other district, no 

 divergence of character could be advantageous. It is this 

 impossibility of advantage in divergence of character in por- 

 tions of a species exposed to the same environment which 



