83 M. Bronn on the Laws of Evolution of the Organic World 



lation of the last chapter, in which M. Bronn himself gives a 

 summary of the essential results at which he has arrived. 



E. Claparede. 



I. Results of the investigations of M. Bronn with regard to the 

 distribution of fossil organisms in the natural series of sedi- 

 mentary strata. 



The investigations containecl in this work are a confirmation 

 of the laws resulting from the purely geological study of the 

 evolution of the crust of the earth in relation to the successive 

 appearance of organized beings. They also bring to light certain 

 facts which do not immediately result from those laws, although 

 they are not in contradiction to them — facts which particularly 

 deserve attention. 



First fundamental law. 



1. Organisms have made their appearance, in the sequence of 

 time and in different localities^ in conditions of type and number 

 which were in relation to the external conditions of existence. 



3. The appearance of the two organized kingdoms was simul- 

 taneous. It dates almost immediately from the first Nep- 

 tunian deposits — that is to say, from an epoch when the central 

 heat must have still exercised a considerable influence upon the 

 surface of the globe. It was undoubtedly, from the first, the 

 business of the organisms of both kingdoms to maintain the 

 atmosphere in such a state that the proportions of oxygen £^nd 

 carbonic acid might be as favourable as possible to their own 

 development, at least if we suppose that the chemical composition 

 of the atmosphere was already constant and independent of 

 other circumstances {vide 8). 



3. The population of the surface of the earth was, originally, 

 very uniform in all latitudes. It is only towards the middle of 

 the tertiary period that we see the floras and faunas become 

 essentially differentiated according to zones. 



4. Both as regards its constitution and number, the primitive 

 population of the surface of the earth corresponded with a hot 

 climate, of tropical nature, uniform throughout the year. This 

 results from the very fact that the climatic differences of the dif- 

 ferent zones were not manifested until a later period, in conse- 

 quence of a refrigeration starting from the polar regions. 



5. All the successive modifications of the animal and vegetable 

 population of the surface of the globe have been effected by the 

 annihilation of the older species and the continual appearance of 

 new species, without there having ever been any gradual passage 

 from one species to another. 



6. The primitive types, whether animal or vegetable, were 



