CH. xiv] GENERAL DISCUSSION 171 



selection was indifferent to them. But if this were so, it could not 

 carry them further. This being so, why not go the whole course at 

 one effort, and admit that selection had little, or perhaps even 

 nothing, to do with the evolution of the organisms that now exist 

 in the world, however much it may have improved them after 

 their evolution, or fitted them to the local conditions in which 

 they were trying to live? Everything, before it can become 

 established, must pass through the sieve of natural selection, and 

 each new individual, in any place, must do the same, but the 

 characters of that new species or individual were not selected by it. 

 If selection does not begin a species or an individual, it has no 

 responsibility for its arrival, but it will kill it out if it be un- 

 suitable to the conditions of the place in which it appears, at the 

 time at which it appears. Why then should natural selection be 

 needed at all for structural change, if it does not begin it, and 

 when one can generally find no adaptational value in it? 



This is very much the position that the author took up in 1907, 

 basing his change of view more or less upon this line of reasoning, 

 and admitting that no mutation that may be needed for the 

 purpose in view — the formation of species, genera, or families — 

 is too large for possibility. There is little or no evidence that 

 structural differences in root, stem, leaf, flower, fruit, seed, have 

 any adaptational value, yet it is these things that make up the 

 characteristic differences that separate one species, genus, or 

 family from another (cf. Thalictrum, etc., on p. 104, and lists in 

 Appendices). There is no evidence that climbing plants (p. 57) 

 have gained by the fact that they can climb. The same genus 

 sometimes contains both climbers and non-climbers, and the 

 former must have erect plants upon which to climb, with few 

 exceptions. Supposing that they smothered all the erect plants 

 by their success, as they might very easily do if really "suc- 

 cessful", both they and the latter would be in a bad way, yet 

 there is nothing to prevent it. 



The view that mutations are necessarily small rests to some 

 extent upon the opinion that a Linnean species is composed of a 

 great assemblage of micro-species which breed true. But it can 

 only be so if it consist of a great number of individuals and 

 occupy a large area. Upon the theory of age and area, as well as 

 upon that of differentiation, this means that it is older than the 

 small and local (allied) species, which is so often Linnean in the 

 sense of marked difference, but cannot show great variety through 

 lack of numbers (p. 132). 



We imagine, then (under the theory of differentiation or diver- 



