124 ISLAND LIFE 



mild climate and luxuriant vegetation of the Arctic zone. 

 If my readers will follow me with the care and attention 

 so difficult and interesting a problem requires and deserves, 

 they will find that I have grappled with all the more im- 

 portant facts which have to be accounted for, and have 

 offered what I believe is the first complete and sufficient 

 explanation of them. The important influence of climatal 

 changes on the dispersal of animals and plants is a suffi- 

 cient justification for introducing such a discussion into 

 the present volume. 



Note. — Readers who are especially interested in the 

 question of the Glacial Epoch, its extent and work, espe- 

 cially in connection with the formation of deep lake-basins, 

 will find much new matter in the two chapters on " The 

 Ice Age and its Work " in the first volume of my Studies 

 Scientific and Social, in which some new arguments founded 

 on the surface and bottom contours of lake-basins are set 

 forth. 



