CHAP. I.] 



INTEODUCTORY. 



7 



not there, a problem which involves all the migrations of these 

 species and their ancestral forms — all the vicissitudes of climate 

 and all the changes of sea and land which have affected those 

 migrations — the whole series of actions and reactions which 

 have determined the preservation of some forms and the ex- 

 tinction of others, — in fact the whole liistory of the earth, 

 inorganic and organic, throughout a large portion of geological 

 time. 



We shall perhaps better exhibit the scope and complexity of 

 the subject, and show that any intelligent study of it was 

 almost impossible till quite recently, if we concisely enumerate 

 the great mass of facts and the number of scientific theories 

 or principles which are necessary for its elucidation. 



We require then in the first place an adequate knowledge of 

 the fauna and flora of the whole world, and even a detailed 

 knowledge of many parts of it, including the islands of more 

 special interest and their adjacent continents. This kind of 

 knowledge is of very slow growth, and is still very imperfect ; ^ 



1 I cannot avoid here referring to the enormous waste of labour and 

 money with comparatively scanty and unimportant results to natural history 

 of most of the great scientific voyages of the various civilized governments 

 during the present century. All these expeditions combined have done far 

 less than private collectors in making known the products of remote lands 

 and islands. They have brought home fragmentary collections, made in 

 widely scattered localities, and these have been usually described in huge 

 folios, whose value is often in inverse proportion to their bulk and cost. 

 The same species have been collected again and again, often described 

 several times over under new names, and not unfrequently stated to be 

 from places they never inhabited. The result of this wretched system is 

 that the productions of some of the most frequently visited and most in- 

 teresting islands on the g;obe are still very imperfectly known, while their 

 native plants and animals are being yearly exterminated, and this is the 

 case even with countries under the rule or protection of European 

 governments. Such are the Sandwich Islands, Tahiti, the Marquesas, the 

 Philippine Islands, and a host of smaller ones ; while Bourbon and Mauritius, 

 St. Helena, and several others, have only been adequately explored after 

 an important portion of their productions has been destroyed by cultiva- 

 tion or the reckless introduction of goats and pigs. The employment in 

 each of our possessions, and those of other European powers, of a resident 

 naturalist at a very small annual expense, would have done more for 

 the advancement of knowledge in this direction than all the expensive 

 expeditions that have again and again circumnavigated the globe. 



