CHAP. I INTRODUCTORY 



years study of this class of subjects has couvmced me that 

 there is no short and easy method of dealing with them ; 

 because they are, in their very nature, the visible outcome 

 and residual product of the whole past history of the 

 earth. If we take the organic productions of a small 

 island, or of any very limited tract of country, such as a 

 moderate-sized country parish, we have, in their relations 

 and affinities — in the fact that they are there and others 

 are not there, a problem which involves all the migi-ations 

 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 extinction of others, — 

 in fact the whole history 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 know- 

 ledge 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 ; ^ and in many cases it can 



^ I cannot avoid liere referring to tlie 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 or f^uartos, 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 unfref[uently 

 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 interesting islands on the globe 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 



