CH. IV] THE HOLLOW CURVE 39 



for example, outside the island, was found to go, on the average, 

 with their distribution inside the island,^ but natural selection 

 could not adapt a plant that was to come, say from West Africa, 

 to suit Ceylon better than a plant that had only come, say from 

 Bombay. If anything, one would expect the latter to suit Ceylon 

 the better. And the same thing showed with the names of the 

 farmers. Rochat is a very common name in the valley of Joux, 

 and has spread farthest into the country round, while the names 

 that are less common have spread less. It is impossible to main- 

 tain that the possession of the name Rochat gives any advantage 

 in the struggle for existence as against the name Capt, which is 

 less common in Joux, and has not spread so far beyond it (fig. 6). 

 Natural selection can have nothing to do with the distribution of 

 surnames, which behave just like species of plants. 



All these various curves match, and must be determined by 

 the same rules. There would seem to be a necessity to reconsider 

 the idea that distribution is determined by natural selection, as 

 indeed we have already seen. Adaptation can only be to the con- 

 ditions that exist round about the plant, and it is absurd to 

 suppose that the bulrush or the silverweed, for example, that 

 (in the same specific form) occurs in New Zealand as well as in 

 Europe could have become, in Europe let us say, adapted to 

 New Zealand conditions. That it suits them is simply due to luck, 

 and to local adaptation, as it slowly moved from place to place. 

 But in any place where it was not fairly well suited, it would 

 usually be killed out remorselessly and promptly by natural 

 selection. 



Many other cases might be brought up, but the fact that distri- 

 bution shows these hollow curves, which cannot be explained by 

 aid of the theory of natural selection, will suffice to show that 

 that theory in its turn is meeting with almost insuperable diffi- 

 culties. It was difficulties like this which made my friend 

 Dr Guppy, who had devoted most of his life to the study of 

 distribution, adopt in 1906 the theory of evolution by diff'eren- 

 tiation, whilst, as the result of completely independent investiga- 

 tions upon different lines, I myself adopted it in 1907. The theory 

 itself is pre-Darwinian. The idea that underlies it, as formulated 

 by Guppy, is that in the early days of the flowering plants the 

 climates of the world were damper and more uniform. The world 

 as a whole seems to have become drier since that time, so that the 



^ I.e. a plant widely distributed in Ceylon was on the average widely 

 distributed outside it. 



