CH. xiii] D. GEOGRAPHICAL DISTRIBUTION 161 



is capable of explaining problems like these, which occur in 

 hundreds and all closely similar. Natural selection is completely 

 incompetent to do so. What Anemone shows in the Indian region 

 is a contour map, which we have already shown on p. 149 to be 

 completely favourable to differentiation and to age and area. 



TEST CASE XXXI. LARGE GENERA THE 

 MOST "SUCCESSFUL" 



One cannot accept the large genera as the most successful in the 

 light-hearted way in which this has been done under natural 

 selection. They are not usually composed of numbers of widely 

 distributed species — their successes are limited to comparatively 

 very few. We have seen above how few of the numerous Siparunas 

 or MolUnedias are widely distributed, and yet these are by far 

 the largest genera in their family. And the same phenomenon is 

 almost universal. If we take as another example the Styraceae, 

 of which the monograph is lying beside me, we find a family of 

 six genera, four with three species each, one with two, and Styrax 

 itself with 100. Here surely is a family with one conspicuously 

 successful genus. But when we look at the whole distribution, 

 there are only four widely dispersed species in the whole family, 

 one in Pterostyrax and three in Styrax. The distinction between 

 these genera is mainly that one has a superior, the other an in- 

 ferior, ovary. Upon the hypothesis of natural selection, therefore, 

 the family consists of about four successful species and 110 relics. 

 And not only so, but the Styrax that is by far the most widely 

 dispersed has a very discontinuous distribution (W^. As., Eur.; 

 W.N.Am.), a thing that does not occur with the small genera, 

 usually looked upon as relics. It is much simpler to regard the 

 widely distributed species as older, the local as younger, as differ- 

 entiation requires. 



TEST CASE XXXIL CHARACTERS MORE CONSTANT 



THE MORE USEFUL 



This is sometimes advanced as a corollary of the theory of 

 natural selection, and indeed it seems almost necessarilv to 

 follow. How much substance there is in the argument, however, 

 may be judged from the fact that the most constant characters 

 in plants are notoriously those that are the most important in the 

 classification (for the obvious reason that they are the most 

 constant). But the higher one goes in the classificatory characters, 

 from those of species to those of families, the more constant do 



WED II 



