206 LIFE ON THE EARTH. 



died out, while others came into view; the whole 

 theatre of life always full of action, but the actors 

 continually changing, however slow the process of 

 change. 



But, as already observed, the evidence of most 

 value for deciding the probability of such a pro- 

 gressive change in the forms of life is to be furnished 

 by geology. That it does not furnish good evidence 

 in favour of gradual and indefinite change is perhaps 

 generally allowed ; but that it does furnish evidence 

 of interrupted and limited change, and that the 

 changes mark steps of progress, is a prevalent opinion. 

 It is the opinion of Mr Darwin, that if the record 

 of life in the fossiliferous strata were complete, those 

 changes which now appear interrupted and sudden 

 would be found to have been continuous, and the 

 progress by steps would become an inclined plane 

 of easy ascent. This incompleteness he assumes to 

 be enormous ; so much so that the traces of whole 

 periods of immense duration, including the first 

 period, are lost ; what we possess being merely frag- 

 ments of the record, which indeed never was com- 

 plete, owing to the character of some kinds of 

 deposits. Thus we must not expect to be able to 

 arrange the fossil remains in a real however broken 

 series, since the true order and descent may be, and 

 for the most part is, irrecoverably lost. . 



