280 
ISLAND LIFE. 
[part ii. 
it is almost exclusively migratory birds that annually reach the 
Azores and Bermuda; while the corresponding fact that the 
seeds of those plants, which are common to the Galapagos and the 
adjacent continent, have all — as Sir Joseph Hooker states — some 
special means of dispersal, is equally intelligible. The reason 
why the Galapagos possess four times as many peculiar species 
of plants as the Azores is clearly a result of the less constant 
introduction of seeds, owing to the absence of storms ; the 
greater antiquity of the group, allowing more time for specific 
change ; and the influence of cold epochs and of alterations 
of sea and land, in bringing somewhat different sets of plants at 
different times within the influence of such modified winds and 
currents as might convey them to the islands. 
On the whole, then, we have no difficulty in explaining the 
probable origin of the flora and fauna of the Galapagos, by 
means of the illustrative facts and general principles already 
adduced. 
