4 THE DARWINIAN THEORY [ch. i 



like those from which it came that the conditions are, the better 

 chance will the young plant have, whereas if it come from some 

 distance, where the conditions are likely to be somewhat dif- 

 ferent, it will be more a matter of good luck should it succeed in 

 establishing itself in the new locality. 



As competitors begin to decrease, the struggle for existence 

 will probably become somewhat less intense. When mature, the 

 struggle will be largely that to secure the most of any small space 

 for expansion of roots or of leaves that may become vacant. 



Seeing a struggle like this, it seems natural to suppose that if 

 any of the youngsters possessed any character that might give it 

 any advantage against the rest, however slight, it would tend to 

 win in the struggle more often than not. It is a remarkable thing 

 that inasmuch as evolution is only clearly shown in structural 

 characters, and natural selection was trying to explain evolution, 

 it ignored the functional characters, and tried to explain the 

 structural ones. But of course if the functional characters had 

 been the only ones that were acted upon, there would have been 

 little to show that any evolution had gone on at all. There would 

 obviously be no need for all the structural differences. 



Assuming that the advantageous character were inherited, 

 another plant might win in the next generation, and so on, the 

 character perhaps (another assumption) becoming more and 

 more marked in each generation until at last, when taken 

 together with other characters that had also varied (whether in 

 correlation with the first, or also under the influence of selection), 

 a specific difference was arrived at, and a new species would have 

 been formed. As this would have been formed by a definite 

 adjustment to the local conditions, it would be what is usually 

 called adapted to them ; this type of adaptation we shall call in 

 future structural adaptation, as it was in structure that the 

 changes were supposed to show that had brought the advantages 

 with them. As it would tend to be the unimproved offspring of 

 the old species, which retained its specific characters, that would 

 be defeated in the struggle for existence, the old species would 

 thus tend to decrease in numbers, being gradually reduced to the 

 rank of a small and local group of plants, which might be looked 

 upon as a relic of former vegetation, and which in time would die 

 out altogether. And, supposing the original species to be found 

 upon a considerable area, where there might be differences in 

 conditions between different parts, then it might vary in two or 

 more directions, giving rise to two or more species. In this case 



