INSULAR PLANTS AND INSECTS. 267 



deficiency of smell and taste. We can hardly believe, 

 however, that this would apply to white-coloured butter- 

 flies ; and this may be a reason why the effect of an 

 insular habitat is more marked in these insects than in 

 birds or mammals. 



It is even possible that this relation of sense-acuteness 

 with colour may have had some influence on the 

 development of the higher human races. If light tints 

 of the skin were generally accompanied by some de- 

 ficiency in the senses of smell, hearing, and vision, the 

 white could never compete with the darker races so long 

 as man was in a very low or savage condition, and 

 wholly dependent for existence on the acuteness of his 

 senses. But as the mental faculties became more fully 

 developed and more important to his welfare than mere 

 sense-acuteness, the lighter tints of skin and hair and 

 eyes would cease to be disadvantageous whenever they 

 were accompanied by superior brain-power. Such varia- 

 tions would then be preserved ; and thus may have 

 arisen the Xanthochroic race of mankind, in which we 

 find a high development of intellect accompanied by a 

 slight deficiency in the acuteness of the senses as com- 

 pared with the darker forms. 



Relations of Insular Plants and Insects. I have 

 now to ask your attention to a few remarks on the 

 peculiar relations of plants and insects as exhibited 

 in islands. 



Ever since Mr. Darwin showed the immense import- 

 ance of insects in the fertilization of flowers, great 

 attention has been paid to the subject, and the relation 

 of these two very different classes of natural objects 



