PROBLEMS OF DISTRIBUTION AND THEIR SOLUTION. 139 



as placid an existence under the Czar as under British rule : a 

 kangaroo will live as successfully beneath Dutch as under English 

 sovereignty ; but there may be more prospect of length of days 

 for the hippopotamus under existing circumstances than under an 

 extension of civilisation in the north of Africa. Neglecting, then, 

 the political divisions of the world, the biologist divides the earth's 

 surface into regions, the boundaries of which are determined solely 

 by the distribution of the animals and plants included within their 

 limits. Sweeping aside the lines of demarcation which human 

 powers and aims have constructed, the naturalist constructs a new 

 biological geography, whose continents and countries are under the 

 unceasing sway and sovereignty of those natural forces, agencies, and 

 laws which from all time past have affected the destinies of the earth 

 and its tenants. It is on the very threshold of distribution that we 

 begin to note the wide variations between the former and present 

 methods of studying life's development over the globe's surface. 

 Formerly, the range of any living being was denoted simply by the 

 name of the country or continent in which it occurred. 



But it is evident that such a method of indicating an animal's 

 territory is in the highest degree indefinite. To speak, for instance, 

 of India as the habitat of the tiger, is to imperfectly indicate the 

 range of that animal, which extends over at least two-thirds of 

 the continent, besides being found in the Eastern Archipelago. 

 Or, if we select one or two common British quadrupeds, we 

 may find the anomalies of the common method of naming the 

 habitats of animals to be equally well represented. For instance, 

 the badger is commonly described as being found in Europe. Such 

 a method of denoting its range tends to imply that its distribution is 

 limited to that continent. But in point of fact, the badger ranges 

 eastwards from Central Asia to Amoor, and southwards to North 

 Africa as well. The otter's distribution ranges to North Africa, and 

 extends to Siberia ; the hedgehog is found from Central Asia to 

 Amoor, like the badger ; and the mole extends as far as Central 

 Asia. Certain of our birds fall equally without the common indica- 

 tions of distribution. Our grey wagtail (Motadlla sulphurea) extends 

 to North Africa, and occurs also in Central Asia, China, and 

 Malaya ; and the house-sparrow, fieldfare, starling, and crow, have a 

 distribution varying from Britain to North Africa and Central Asia. 

 The inadequacy of ordinary descriptive geography to indicate the 

 range of these animals can therefore be readily understood. In the 

 nature of things, the distribution of animals and plants follows certain 

 laws which have left their impress upon the boundaries of land-regions 

 likewise. It remains for us to see how the earth's surface has been 

 mapped out by these laws into natural continents or regions, each 

 characterised by its own characteristic fauna and flora. The popular 



