408 OK THE SUCCESSIVE FORMS 



are those which existed, as animals, in the ocean of 

 the second condition here enumerated, being that under 

 which the primary strata were formed, and, probably, 

 as vegetables, on the land of that second earth. There 

 are also reasons to conclude that there has been a pro- 

 gressive increase of the numbers of animals in succes- 

 sive states of the globe, or, that the number in any 

 one condition was greater than that in the preceding; 

 as the present population seems, similarly, more abun- 

 dant than that immediately prior. If that can not be 

 satisfactorily proved by the absolute presence of the 

 organic fossils themselves, it is safely inferred from 

 the gradual and successive increase of calcareous strata: 

 and thus does the presence of coal, including the later, 

 or the lignites, with the great coal deposits, indicate the 

 existence of a vegetable surface in the earth, from its 

 fourth condition onwards; though there is, in this case, 

 no proof of a regular increase in the numbers or quan- 

 tity of plants, analogous to what we conclude of animals 

 from the constant increase of the calcareous strata. 



Thus the state of the earth has been meliorated by 

 some, if not by all of its changes; or it has bcenrcndcrcd 

 successively more fit for the habitation of succeeding 

 races of animals. The last improvement which it has 

 undergone, in the newest calcareous strata, so much 

 exceeding former ones, is palpable; as every fresh 

 change appears to add new races, or at least to increase 

 numbers, while the revolutions which follow, though 

 they should destroy their forms with their lives, or 

 destroy those preserved from antecedent worlds, leave 

 the calcareous earth into which they are resolved, un- 

 changed. In their present state, the softer spoils of 

 animals form a manure for that land which supports 

 the existing races of animal life by its vegetable pro- 

 duce. Their harder parts, accumulated through the 

 various revolutions of the globe, tend equally to in- 



