133 STUDIES IN LIFE AND SENSE. 



habits of all living things are also slowly changing; while the 

 great features of the earth, the continents, and oceans, and loftiest 

 mountain ranges, only change after very long intervals, and with 

 extreme slowness ; we must see that the present distribution of 

 animals upon the several parts of the earth's surface is the final 

 product of all these wonderful revolutions in organic and inorganic 

 nature." 



The proposition that in the existing world we may find a reflex 

 of those causes which have wrought out the scheme of life's distribu- 

 tion over the surface of the globe, has received the tacit sanction and 

 approval of all competent biologists. This result has been attained 

 through the slow but sure and progressive advance of modern ideas 

 concerning the uniformity of natural law and physical causation. 

 The teachings of evolution in biology are but the reflections of 

 " uniformity " in geology. As the doctrine of uniformity has taught 

 us that the physical forces represented in and by the internal heat, 

 water, frost, snow, and chemical action are the agencies which from 

 all time past have been sculpturing and moulding our earth's features 

 as we trace in the physical actions of the present the key to the 

 activities of the past so in biology we assume, and assume logic- 

 ally, that the ordinary activities of life, the processes of variation and 

 change and the influence of environments on the living form, are the 

 agencies which mould the world of life now, as in the earliest seons, 

 and as in the beginning itself. Rejecting the idea of uniformity in 

 science, we fall back on the catastrophism of primitive geology and 

 on the " special creation " of those early times of biology, when 

 fabulous theory represented the exact observation of to-day. Ac- 

 cepting, however, the theories of " uniformity " in the inorganic world 

 and of " evolution " in the living universe, we unite the sciences in 

 a circle, outside the magnificent unity of which no fact of inorganic 

 nature or of the living world can be presumed to exist. 



The division of the world's surface for the purposes of ordinary 

 geography is obviously unsuited to the wants of the biologist. The 

 geographical survey of the earth is of necessity a matter of politics. 

 The greater nation tends to obliterate the smaller; allocation of 

 territory is largely a matter of division of spoil ; and the outlines and 

 boundaries of the countries of the world reflect the kaleidoscopic 

 change which marks the arena of political strife and its concomitant 

 warfare for its own. For scientific purposes, then, the standpoints 

 of the political geographer are unavailable. Save in so far as the 

 march of civilisation means and implies the destruction and repres- 

 sion of the animals and plants which are either useful or useless 

 and dangerous to man, the distribution of life on the globe is com- 

 paratively unaffected by the divisions whereby man demarcates his 

 territorial possessions from those of his neighbours. A rat may pass 



