54 CONTACTS WITH DARWINISM IV [ch. vi 



classification and distinction, and even showing, in many cases, 

 both members of the contrasting pairs that are given in the list of 

 family characters (Appendix I). These characters show no relation 

 whatever to any of the ecological features that may give the 

 character to the locality. Almost any family or genus, if large 

 (i.e. old, upon the theory of Age and Area, with its subsidiary 

 Size and Space) may be found in almost any kind of locality, 

 represented by some of its species. For example, in the bog flora 

 just mentioned, there occurs Sedum villosum, a member of a large 

 genus of 450 species usualh^ xerophytic. And not only so, but it 

 is a hairy species, bearing a character usually specially associated 

 with xerophytism. Morphologists have long maintained that 

 structural characters have nothing to do, directly, with the life 

 or functions of the plant, and it would appear that they are right 

 in this contention, which violently contradicts the supposition of 

 selection as a chief cause in evolution. The evolution that has 

 produced more than 12,000 genera and 180,000 species has not 

 been, primarily, an adaptational evolution, as the writer tried to 

 show twenty-five years ago in the case of the Podostemaceae. 



The agency by which plants were to become adapted to the 

 conditions in which they were found was, of course, that of 

 natural selection, for the competition upon which it is based, 

 which we call the struggle for existence, will evidently kill out 

 those that are in any way seriously unsuited to the conditions. 

 It may also kill out some or many of those that are well suited, if 

 they be in any way handicapped, as by too shady a position when 

 in the seedling stage, by a poor water supply, or by many other 

 things. But in itself this killing out would not produce any 

 advance in complexity of structure or function, the things that 

 we regard as showing that evolution has gone on. Certain assump- 

 tions were therefore needed. Only advantageous changes could 

 be picked out, and it was therefore supposed that (usually) when 

 a gradual change of local conditions began, some of the offspring 

 varied in such a direction as to give them an advantage. It had 

 also to be assumed that the parent did not vary in this way. The 

 process being repeated in every generation (another assumption), 

 the improved forms always winning, the difference from the 

 parent ultimately became specific, showing as a rule more or less 

 sterility when crossed with the parent. The parent was supposed 

 not to adapt itself (yet another assumption), but to become a 

 relic and gradually to die out for want of offspring viable in the 

 new conditions. 



