II.] INCIPIENT STRUCTURES. 61 



How, then, could either the minute incipient stages, or 

 the final . perfecting touches of this admirable structure, 

 have been brought about by vague, aimless, and indelinite 

 variations in all conceivable directions of an organ suited 

 to enable the rudest savage to minister to his necessities, 

 but no more ? 



Mr. Wallace 1 makes an analogous remark with regard to 

 the organ of voice in man the human larynx. He says 

 of singing: "The habits of savages give no indication of 

 how this faculty could have been developed by Natural 

 Selection, because it is never required or used by them. 

 The singing of savages is a more or less monotonous 

 howling, and the females seldom sing at all. Savages cer- 

 tainly never choose their wives for fine voices, but for rude 

 health, and, strength, and physical beauty. Sexual selection 

 could not therefore have developed this wonderful power, 

 which only comes into play among civilized people." 



Ee verting once more to beauty of form and colour, there 

 is a manifestation of it for which no one will pretend that 

 sexual selection can possibly account. The instance re- 

 ferred to is that presented by bivalve shell-fish. 2 Here we 

 meet with brilliant tints and elegant forms and markings 

 of no direct use to their possessors 3 in the struggle for life, 

 and of no indirect utility as regards sexual selection, for 

 fertilization takes place by the mere action of currents of 

 water, and the least beautiful individual has fully as good 



1 " Natural Selection," p. 350. 



2 Bivalve shell-fish are creatures belonging to the oyster, scallop, and 

 cockle group, i.e. to the class Lamellibranchiata. 



3 The attempt has been made to explain these facts as owing to 

 "manner and symmetry of growth, and to colour being incidental on the 

 chemical nature of the constituents of the shell." But surely beauty 

 depends on some such matters in all cases ! 



