XLIL* 



Slife of Sslanfcs. 



IN dealing with the history of islands in our last paper, 

 I referred to the manner in which animals and plants 

 were enabled to pass from one region to another, and 

 thus to people islands which had been raised from the 

 depths of the sea as independent masses of land. So 

 important however, is the consideration of the ways 

 and means in which this dispersal of life is carried on, 

 that the topic is interesting enough to merit the dis- 

 tinction of our further attention. 



In the case of plants, it is obvious that the vegetable 

 world possesses powers of dispersion which are un- 

 known in the animal realm. Many seeds are furnished 

 with means for conveyance by the wind, and such as 

 are provided with hard shells may be protected for 

 long periods from the action of water. Volcanic islands 

 owe their plant-life to the chance sowing of seeds, 

 borne by the winds or waves to their shores ; and birds 

 also act as important colonisers of such islands through 

 their conveyance of seeds adhering to their plumage, 

 or contained in clods of earth which become attached 

 to their feet. 



In the case of the animal life of islands, we note 

 that certain animals are unfitted by their nature and 

 habits to traverse great distances by sea. Such are 

 quadrupeds, and such are the frogs and their neigh- 



