CHAr. I.] 
INTRODUCTORY. 
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 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 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 
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 globe are still very imperfectly known, while their 
native plants and animals are being yearly exterminated, and this is the 
case even with eountries 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. 
