EXTEIsTSIONS OF DARWINISM 277 



small. But I have shown in the early chapters of this book 

 (and much more fully in my Darwinism) that all these as- 

 sumptions are the very reverse of the known facts. The 

 numbers of varying individuals in any dominant species (and 

 it is only these which become modified into new species) is 

 to be counted by millions ; and as the whole number can, as 

 regards any needed modification, be divided into two lialves 

 — those which possess the special quality required above or 

 below the average — it may be said thali nearly half the total 

 number vary favourably, and about one-fourth of the whole 

 number in a very large degree. Again, it has been shown 

 that the number of coincident variations are very great, since 

 they are always present when only a dozen or twenty individ- 

 uals are compared; bnt nature deals with thousands and mil- 

 lions of individuals. Yet, again, we know that changes of the 

 environment are always very slow as measured by years or 

 generations, since not a single new species is known to have 

 come into existence during the whole of the Pleistocene period ; 

 and as fresh variations occur in every generation, almost any 

 character, with all its co-ordinated structures, would be con- 

 siderably modified in a hundred or a thousand generations, and 

 ■we have no absolute knowledge that any great change would 

 be required in less time than this.^ 



lA very familiar fact will, I think, show that a large amount of co- 

 ordinated variability in different directions does actually occur. First-rate 

 bowlers and wicket-keepers, as well as first-rate batters, are not common in 

 proportion to the whole population of cricket-players. Each one of these 

 requires a special set of co-ordinated faculties — good eyesight, accurate 

 \ perception of distance and of time, with extremely rapid and accurate re- 

 sponse of all the muscles concerned in the operations each has to perform. 

 If all the special variations required to produce such individuals were sot 

 forth by a good physiologist in the detailed and forcible manner of the 

 passage quoted from Spencer about the giraffe, it would seem impossible 

 that good cricketers should ever arise from the average family types. Yat 

 they certainly do so arise. And just as cricketers are chosen, not by ex- 

 ternal characters, but by the results of actual work, so nature selects, not by 

 special characters or faculties, but by that combination of characters which 

 gives the greatest chance of survival in the complex, fluctuating environment 

 in which each creatures lives. The species thus lK»comes adapted, first to 



