232 THE LAW. 



[Influence of Man on the Future.] 



The removal and extinction of species, viewed in con- 

 nection with the physical changes that are continually taking 

 place on the surface of the globe, necessarily lead to specu- 

 lations as to the conditions and phases of the FUTURE. 

 Eespecting these, however, it seems vain to offer even the 

 widest conjecture, so long as we remain in ignorance of the 

 law that has regulated the progression of the Past. Where 

 the terms of a law are known, the formulae may be readily 

 framed for the calculation of its times and results ; but where 

 these terms are little better than guessed at, our reasonings 

 can never rise beyond the value of the merest hypotheses. 

 Subjected as our planet is to numerous modifying causes, 

 we know, however, that vast changes are ever in progress, 

 and that the present aspects of nature will not be the same 

 as those she must assume in the eras that are to follow. 

 But what may be the nature and amount of these changes, 

 what the new conditions brought about by them, or what 

 the races of plants and animals adapted to these conditions, 

 science has yet no available means of determining. And 

 yet, as we have seen that in past ages certain species of one 

 epoch always passed less or more numerously into the suc- 

 ceeding epoch, so it is not unreasonable to presume that 

 many of the existing species will pass into the period which 

 is to follow. We have also seen that though in certain 

 regions extinctions took place rapidly and entirely, yet over 

 the whole world the progress of vitality has been gradual 

 and continuous ; and, generalising in like manner for the 

 future, it is surely allowable to presume on a similar con- 

 tinuity and gradation. We have also seen that whatever 

 the specific phases of vitality, they never diverged beyond 

 certain limits, but were ever constructed after a few grand 



