SELECTION: ORGANIC AND SOCIAL 207 



of chance and non-direction in the origin of a large 

 number of adaptive and other new characters, is 

 the common working principle both ia Vertebrate 

 and Invertebrate palaeontology." * 



(e) Another change of view— rank heresy to those 

 of the straiter sect of Darwinians — is seen in the 

 writings of not a few naturalists who do not feel 

 themselves bound to find a use for everything. 

 There are many apparently trivial characters for 

 which careful investigation has discovered very 

 definite and unexpected utility — Weismann gives, 

 as an example, the beautiful microscopic anchors 

 and discs of Ume found in the skin of the burrow- 

 ing, worm-like Holothurians known as Synaptids ; 

 but, on the other hand, the tyranny of an ex- 

 treme zoological utilitarianism may become absurd. 

 When the wind blows the long, sharp-pointed leaf 

 of the sand-binding bent-grass it often makes a 

 perfect circle on the sand, but there is no signifi- 

 cance in this. Nor is there in the beautiful ripple- 

 marks on the sand or in the frost-flowers in the 

 window. It seems Ukely that there are many 

 such things in Hving creatures — registrations of 

 orderly rhythms of the body, but not useful. The 

 barring on a feather may be of life-saving value, 

 it may also mean nothing more than diurnal 

 variations in blood-pressure when the feather was 

 a-making. 



Sexual Selection. — ^Aa a corollary to his 

 theory of natural selection, Darwin expounded a 

 theory of sexual selection, in which he interpreted 

 some of the secondary peculiarities of the sexes 

 as the outcome of selective processes involved in 

 the combats of rival suitors and in the choice 



» Op. cit. (1909). 



