1893 ON SELF-ADAPTATION 329' 



I would limit natural selection, as far as plants 

 are concerned, to three things : 



1. Mortality among seedlings with the survival of 

 the strongest. 



I do not say 'fittest,' because it is ordinarily 

 understood to mean that the survivors have some 

 morphological features, by which they are benefited, 

 which lead on finally to specific characters. 



I do not find this to be the case. Take an 

 instance of great contrast. Sow 100 seeds of the 

 water (submerged) Ranunculus fluitans in a garden. 

 They all grow up as aerial plants, i.e. they vary as 

 they grow precisely in the same way. It is only 

 the weakest (from badly nourished seeds) which get 

 crowded out of existence. Here, then, is definite 

 variation without the aid of natural selection. Ex uno 

 disce omnes. 



2. Delimitation of varieties and species by the 

 non-reproduction of intermediate forms. 



It is generally said that if ' good species ' are 

 isolated, the intermediate forms have been killed off 

 by natural selection. I maintain that they were 

 never reproduced. Thus if a has passed by succes- 

 sive generations, a', a", a'", &c., to a° ; a and a° being 

 now only in existence, then a', a", &c., represented a 

 single generation apiece, each offspring being one 

 degree nearer to a", but could never be reproduced, 

 as the environment was continually acting upon the 

 whole series, urging each generation forwards till it 

 became stable in a''. 



This is precisely what takes place in cultivating a 

 wild plant like the parsnip. Each year the grower 



