314 WHAT OF THE FUTURE? 



southerly and warmer latitudes. But the mere lying 

 within more southerly latitudes does not altogether de- 

 termine the nature of a climate or the geniality of external 

 conditions. Insular or continental arrangement of the land- 

 masses, altitude above the sea-level, the direction of moun- 

 tain-ranges and valleys, the amount of rainfall, and the set 

 of ocean-currents from colder or warmer regions, all influence 

 less or more the climate of a country ; and these, as affecting 

 the future lands of our globe, we have no means whatever 

 even of guessing at. All that we know for certain is, that 

 the existing continents are gradually passing into newer 

 forms and dispositions, and that these dispositions must 

 of necessity be accompanied by other climates and by other 

 vegetable and animal appointments. All that we can offer 

 as a legitimate geological inference is, that the land-masses 

 more immediately succeeding the existing will be more sub- 

 tropical and tropical in their position, and, cceteris paribus, 

 more congenial in their physical surroundings. 



In the third place, if the present continents and islands 

 are to be superseded by others possessed of different ex- 

 ternal conditions, it follows that these newer lands must be 

 characterised by different distributions of plants and animals. 

 At present it is presumed that each plant and animal oc- 

 cupies the station and habitat best suited to its growth and 

 perfection ; but if these situations be interfered with, no 

 matter how slowly, certain races must succumb to the change, 

 while others will usurp their places. Were the future con- 

 tinents, for example, to be gradually evolved within lower 

 latitudes, their flora and fauna would as gradually assume 

 a tropical aspect existing forms, on the other hand, dis- 

 appearing stage by stage with the external conditions to 

 which they had been originally adapted. The disposition 

 of the existing continents is mainly longitudinal, hence they 



