ADDRESS. 23 



furnislies at least a presumption in favour of the extremely tardy progress 

 of organic variation. 



If, however, we extend our vision beyond the narrow range of human 

 history, and look at the remains of the plants and animals preserved in 

 those younger formations which, though recent when regarded as parts 

 of the whole geological record, must be many thousands of years older 

 than the very oldest of human monuments, we encounter the most 

 impressive proofs of the persistence of specific forms. Shells which 

 lived in our seas before the coming of the Ice Age present the very same 

 peculiarities of form, structure, and ornament which their descendants 

 still possess. The lapse of so enormous an interval of time has not 

 sufficed seriously to modify them. So too with the plants and the higher 

 animals which still survive. Some forms have become extinct, but few 

 or none which remain display any transitional gj-adations into new 

 species. We must admit that snch transitions have occurred, that indeed 

 they have been in progress ever since organised existence began upon our 

 planet, and are doubtless taking place now. But we cannot detect them 

 on the way, and we feel constrained to believe that their march must be 

 excessively slow. 



There is no reason to think that the rate of organic evolution has ever 

 seriously varied ; at least no proof has been adduced of such variation. 

 Taken in connection with the testimony of the sedimentary rocks, the 

 inferences deducible from tossils entirely bear out the opinion that the 

 building np of the stratified crust of the earth has been extremely 

 gradual. If the many thousands of years which have elapsed since the 

 Ice Age have produced no appreciable modification of surviving plants 

 and animals, how vast a period must have been required for that 

 marvellous scheme of organic development which is chronicled in the 

 rocks ! 



After careful reflection on the subject, I affirm that the geological 

 record furnishes a mass of evidence which no arguments drawn from 

 other departments of Nature can explain away, and which, it seems to 

 me, cannot be satisfactorily interpreted save with an allowance of time 

 much beyond the narrow limits which recent physical speculation would 

 concede. 



I have reserved for final consideration a branch of the history of the 

 earth which, while it has become, within the lifetime of the present gene- 

 ration, one of the most interesting and fascinating departments of geo- 

 logical inquiry, owed its first impulse to the far-seeing intellects of Hutton 



