422 THE DISTRIBUTION OF ANIMALS AND PLANTS 



existence, but facilities for easy existence and rapid extension, 

 that afford the conditions necessary for new and advanced 

 forms of life. These considerations do not, of course, reach 

 to the first cause of the introduction of species, nor even to 

 the precise mode in which this may have acted in any parti- 

 cular case : but perhaps we cannot fully attain to this by any 

 process of inductive inquiry. The study of geographical dis- 

 tribution,' therefore, does not enable us to solve the question 

 of the origin of specific types, but, on the contrary, points to 

 marvellous capacities for migration and a wonderful tenacity 

 of life in species. In these respects, however, it is a study 

 full of interest, and in nothing more so than in the evidence 

 which it affords of the practically infinite provisions made for 

 the peopling of every spot of land or sea with creatures fitted 

 to flourish and enjoy life therein, and to carry on the great 

 and progressive plan of the Creator. 



REFERENCES : Continental and Island Life, Princeton Review, July, 1881. 

 Address to American Association, 1883. Papers and Addresses to 

 Natural History Society, Canadian Naturalist, Montreal. "The 

 Story of the Earth and Man," 1st ed., 1873, gth ed., London, 

 1887. 



