480 
ISLAND LIFE. 
[part II. 
identical with European species. These islands are more than 
800 miles from Europe, and, as we have already seen in Chapter 
XII., there is no reason for supposing that they have ever been 
more nearly connected with it than they are now, since an exten- 
sion of the European coast to the 1,000-fathom line would very 
little reduce the distance. Now it is a most interesting and 
suggestive fact that more than half the European genera which 
occur in the Australian flora occur also in the Azores, and in 
several cases even the species are identical in both. 1 The im- 
portance of such a case as this cannot be exaggerated, because 
it affords a demonstration of the power of the very plants in 
question to pass over wide areas of sea, some no doubt wholly 
through the air, carried by storms in the same way as the 
European birds and insects which annually reach the Azores, 
others by floating on the waters, or by a combination of the two 
methods ; while some may have been carried by aquatic birds, to 
whose feathers many seeds have the power of attaching them- 
selves. We have in such facts as these a complete disproof of 
the necessity for those great changes of sea and land which are 
continually appealed to by those who think land-connection the 
only efficient means of accounting for the migration of animals 
or plants ; but at the same time we do not neglect to make the 
fullest use of such moderate changes as all the evidence at our 
command leads us to believe have actually occurred, and 
especially of the former existence of intermediate islands, so 
often indicated by shoals in the midst of the deepest oceans. 
Means by which Plants have migrated from North to South . — 
But if plants can thus pass in considerable numbers and variety 
over wide seas and oceans, it must be yet more easy for them to 
traverse continuous areas of land, wherever mountain-chains 
offer suitable stations at moderate intervals on which they might 
temporarily establish themselves. The facilities afforded for 
the transmission of plants by mountains has hardly received 
sufficient attention. The numerous land-slips, the fresh sur- 
faces of broken rock and precipice, the debris of torrents, and 
the moraines deposited by glaciers, afford numerous unoccupied 
1 Hooker, On the Flora of Australia, p. 95. — H. C. Watson, in Godman’s 
Azores, pp. 278-286. 
