106 • KEPOKT— 187G. 



13 to perfect vision. We can therefore understand why white cats with hlue ejes 

 are so often deaf, a peculiarity we notice more readily than their deficiency of smell 

 or taste. 



If, then, the prevalence of white coloration is generally accompanied with some 

 deficiency in the acuteness of the most important senses, this colour becomes 

 doubly dangerous ; for it not only renders its possessor more conspicuous to its 

 enemies, but at the same time makes it less ready in detecting the presence of 

 danger. Hence, perhaps, the reason why white appears more frequently in islands, 

 where competition is less severe and enemies less numerous and varied. Hence, also, 

 a reason why albinoism, although freely occurring in captivity, never maintains 

 itself in a wild state, while melanism does. The peculiarity of some islands in 

 ha\ing all their inhabitants of dusky colours (as the Galapagos) may also perhaps 

 be explained on the same principles ; for poisonous fruits or seeds may there abound 

 which weed out all white- or light-coloured A'arieties, owing to their deficiency of 

 smell and taste. We can hardly believe, however, that this would apply to white- 

 coloiu-ed butterflies ; and this may be a reason why the efl'ect of an insiilar habitat 

 is more marked in these insects than in birds or mammals. But though inappli- 

 cable to the lower animals, this cm-ious relation of sense-acuteuess with colours 

 may have had some influence on the development of the higher human races. If 

 light tints of the skin were generally accompanied by some deficiency 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 ou tlie 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 variations would then be 

 preserved ; and thus may have arisen the Xanthochroic race of manliiud, in which 

 we find a high development of intellect accompanied by a slight deficiency in the 

 acuteness of the senses as compared with the darker forms. 



I have now to ask your attention to a few remarks en the peculiar relations of 

 plants and insects as exhibited in islands. 



Ever since Mr. Darwin showed theimmense importance of insects in the fertilization 

 of flowers gi'eat attention has been paid to the subject, and the relation of these two 

 very diflerent classes of natural objects has been found to be more universal and 

 more complex than could have been anticipated. Whole genera and families of 

 plants have been so modified as first to attract, and then to be fertilized by, certain 

 groups of insects ; and this special adaptation seems in many cases to have deter- 

 mined the more or less wide range of the plants in question. It is also known 

 that some species of plants can be fertilized only by particular species of insects ; 

 and the aksence of these from any locality would necessarily present the continued 

 existence of the plant in that area. Here, I believe, will be found the clue to 

 much of the peculiarity of the floras of oceanic islands, since the methods by which 

 these have been stocked with plants and insects Avill be often quite diflerent. 

 Many seeds are, no doubt, carried by oceanic currents, others probably by aquatic 

 birds. Mr. H. N. Moseley informs mo that the albatrosses, gnalls, puffins, tropic 

 birds, and many others nest inland, often amidst dense vegetation, and he believes 

 they often carry seeds, attached to their feathers, from island to island for great 

 distances. In the tropics they often nest on the mountains far inland, and may 

 thus aid in the distribution even of mountain-plants. Insects, on the other hand, 

 are mostly conveyed by aerial currents, especially by violent gales ; and it may 

 thus often happen that totally xmrelated plants and insects may be brought toge- 

 ther, in which case the former must often perish for want of suitable insects to 

 fertilize them. This will, I think, account for the sti'angely fragmentary nature of 

 these insular" floras, and the great differences that often exist between those which 

 are situated in the same ocean, as well as for the preponderance of certain orders 

 and genera. In Mr. Pickering's valuable work on the ' Geogi-aphical Distribution 

 of Animals and Plants,' he gives a list of no less than sixty-six natural orders of 

 plants vnexpedeiVy absent from Tahiti, or which occur in many of the surrounding 

 lands, some being abundant in other islands — as the I.abiataa at the Sandwich 

 Islands. la these latter islands the flora is much richer, yot a large number of 



