10 
ISLAND LIFE. 
[part I. 
dispersal and existing distribution of organisms. The other 
important theory, or rather corollary from the preceding theory 
— that of the permanence of oceans and the general stability 
of continents throughout all geological time, is as yet very 
imperfectly understood, and seems, in fact, to many persons in 
the nature of a paradox. The evidence for it, however, appears 
to me to be conclusive; and it is certainly the most fundamental 
question in regard to the subject we have to deal with : since, 
if we once admit that continents and oceans may have changed 
places over and over again (as many writers maintain), we lose 
all power of reasoning on the migrations of ancestral forms of 
life, and are at the mercy of every wild theorist who chooses to 
imagine the former existence of a now-submerged continent to 
explain the existing distribution of a group of frogs or a genus 
of beetles. 
As already shown by the illustrative examples adduced in 
this chapter, some of the most remarkable and interesting facts 
in the distribution and affinities of organic forms are presented 
by islands in relation to each other and to the surrounding 
continents. The study of the productions of the Galapagos — 
so peculiar, and yet so decidedly related to the American con- 
tinent — appear to have had a powerful influence in determining 
the direction of Mr. Darwin’s researches into the origin of 
species ; and every naturalist who studies them has always been 
struck by the unexpected relations or singular anomalies which 
are so often found to characterize the fauna and flora of islands. 
Yet their full importance in connection with the history of the 
earth and its inhabitants has hardly yet been recognised ; and 
it is in order to direct the attention of naturalists to this 
most promising field of research, that I restrict myself in this 
volume to an elucidation of some of the problems they present 
to us. By far the larger part of the islands of the globe are 
but portions of continents undergoing some of the various 
changes to which they are ever subject ; and the correlative 
statement, that every part of our continents have again and 
again passed through insular conditions, has not been sufficiently 
considered, but is, I believe, the statement of a great and most 
suggestive truth, and one which lies at the foundation of all 
