84 PROBLEMS OF EVOLUTION 



What On the subject of apparently useless characters Dr Russell 

 u^Jless Wallace has in his Darwinism brought to bear a forcible argu- 

 often ment that is constantly becoming still more forcible. One 

 prov b e e s 3 character after another that was thought to serve no purpose 

 adaptation i s being found to be adaptive. Much has been done in this 

 direction since Dr Wallace published his Darwinism. Notably 

 I may mention that Sir John Lubbock has shown that the 

 arrangement of leaves is not haphazard, but is the best 

 calculated for gaining the maximum of sunlight. Sometimes, 

 in the maple (Acer campestre) for instance, we find the leaf stalk 

 varying in length, so that each leaf may find an opening and not 

 be shaded by its neighbours. Often the size to which a leaf 

 grows depends upon the space available ; each fits into its place 

 and helps to form a mosaic ; sunlight is not a thing to be allowed 

 to run to waste. The beech (Fagus sihatica) and horn-beam 

 (Carpinus betulus) afford good examples of such mosaics. Quite 

 recently Karl Groos has made it clear that the play of animals is 

 not due to mere surplus energy, but that it has a definite use, and 

 that no account of evolution that excludes the subject of play 

 can be considered complete. Mr Benjamin Kidd has shown that 

 religion is not a thing apart, but that human evolution, but for 

 it, would long ago have been brought to a standstill. It is no 

 wonder if some evolutionists come to the conclusion that every 

 structure and quality of every organism will eventually turn out 

 to be adaptive. Nevertheless, he is a sanguine man who retains 

 this view when he fixes his thoughts on some of the familiar 

 minute but constant specific distinctions. 



Ill 



VARIATIONS SMALL OR LARGE 



Both small The variations which Natural Selection finds ready to its hand, 

 and large ^ w hich it takes advantage of to make species, are most of them 



important 



to evolu- quite small, but some or them are large or, as they are called, 

 tlon discontinuous. 1 As to the former we have to show that they 



1 I shall use the simple word large by preference, as Mr Bateson has associated 

 the term " discontinuous " with a disbelief in evolution by Natural Selection. 



