248 



ISLAND LIFE. 



[part II. 



unknown means of conveyance ; but however this may be, the 

 general character of the land-molluscs is such as to confirm 

 the conclusions we have arrived at from a study of the birds 

 and insects, — that these islands have never been connected 

 with a continent, and have been peopled with living things by 

 such forms only as in some way or other have been able to reach 

 them across many hundred miles of ocean. 



Tke Flora of the Azores. — The flowering-plants of the Azores 

 have been studied by one of our first botanists, Mr. H. C. 

 Watson, who has himself visited the islands and made extensive 

 collections; and he has given a complete catalogue of the 

 species in Mr. Godman's volume. As our object in the present 

 work is to trace the past history of the more important islands 

 by means of the forms of life that inhabit them, and as for 

 this purpose plants are sometimes of more value than any class of 

 animals, it will be well to take advantage of the valuable materials 

 here available, in order to ascertain how far the evidence derived 

 from the two organic kingdoms agrees in character; and also 

 to obtain some general results which may be of service in our 

 discussion of more difficult and more complex problems. 



There are in the Azores 480 known species of flowering-plants 

 and ferns, of which no less than 440 are found also in Europe, 

 Madeira, or the Canary Islands ; while forty are peculiar to the 

 Azores, but are more or less closely allied to European species. 

 As botanists are no less prone than zoologists to invoke former 

 land-connections and continental extensions to account for the 

 wide dispersal of objects of their study, it will be well to 

 examine somev/hat closely what these facts really imply. 



The Dispersal of Seeds. — The seeds of plants are liable to be 

 dispersed by a greater variety of agents than any other organisms, 

 while their tenacity of life, under varying conditions of heat and 

 cold, drought and moisture, is also exceptionally great. They 

 have also an advantage, in that the great majority of flowering 

 plants have the sexes united in the same individual, so that a 

 single seed in a state fit to germinate may easily stock a whole 

 island. The dispersal of seeds has been studied by Sir Joseph 

 Hooker, Mr. Darwin, and many other writers, who have made 

 it sufficiently clear that they are in many cases liable to be 



