128 TEST CASES [ch. xi 



Nothing but common descent will explain most of these, and, 

 if so, the family must have been very ancient, and why are there 

 no fossil traces of any family formation, which must have gone on 

 for an immense period of time if they were made by the method of 

 dropping intermediates involved in the explanation by natural 

 selection? Not only so, but the bulk of the characters described 

 in the list above, to which hundreds more might be added, are 

 such that they must have arisen at one step; either no inter- 

 mediates are possible or they would have been completely useless, 

 and therefore incapable of being chosen by selection. 



TEST CASE XVIII. THE SMALL GENERA 



If the small genera are to be regarded as failures and relics, it is 

 somewhat remarkable the way in which they are closely grouped 

 round the large ones, usually regarded as the successes. If one 

 take the two largest genera in a family^ — the two which upon the 

 theory of differentiation represent, upon the average, the result of 

 the first throwing of a new genus by the original genus which was 

 the first parent of the family — one commonly finds them marked 

 by a large divergence. But this same divergence is shown 

 (cf. p. 84) by the groups of "satellite" genera round them, and 

 these include the bulk of those which are classed as relics. Their 

 characters are the chief characters of Ra^iunculus, for example. 

 Upon the theory that Ranunculus owes its success to some of its 

 visible characters, we should expect these to be the characters. 

 Why then are the satellite genera so "unsuccessful"? Very few 

 small genera are known which are not classed in the sub-families 

 which are usually marked each by a fairly important genus at the 

 head. And why should this be, unless the satellites were derived 

 from the large genera? If this happened in the earlier days of the 

 big genera, it is somewhat remarkable that one so rarely finds any 

 fossil traces of the little ones, and if in the later days, w^hy should 

 the big genera throw off, at such a late period, genera that were 

 only to be relics or failures? It seems much more probable that 

 the small genera were thrown off at a late period in the life of the 

 large ones, by some larger change than would give rise merely to 

 new species, but a change that could not have been the result of 

 the work of natural selection. The test favours differentiation 

 much more than it favours natural selection. 



