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



It was, then, the business of these marshy forests to seize upon 

 this carbonic acid and to fix its carbon at the bottom of the 

 waters. In fact, if all the carbon contained in the organic sub- 

 stances now deposited in the sedimentary strata in the form of 

 coal, bitumen, &c, had never existed in the atmosphere in the 

 form of carbonic acid, no animal or vegetable life would have 

 been possible. These coaly marshes of Stigmarice, with their pe- 

 culiar vegetation, seem to have reappeared here and there, when 

 sinkings of the soil, combined with emissions of carbonic acid, 

 again gave rise to similar conditions*. 



9. Although the carbonic acid continually emitted was thus 

 incessantly and slowly eliminated by the Stigmaria-forests, it is 

 not the less probable that the cause of the depression of the 

 soil (elevation of temperature), the carbonic acid contained in 

 the air in greater proportion than at the present day, and the 

 great development of the marshes of Stigmarice all over the surface 

 of the globe, must have exercised a very great influence upon the 

 character of the rest of the vegetation. But these are effects 

 which it is no longer possible to analyse, nor to refer with cer- 

 tainty to their particular causes. 



10. A multitude of plants and animals, especially more than 

 three-fourths of the terrestrial insects, birds, and mammals, 

 which, cither with regard to their food or habitation, are ne- 

 cessarily connected with certain genera, or even certain species 

 of plants, could, of course, only appear after the latter. The 

 inferior plants and animals are often less intimately connected 

 with other organisms than others which are higher in the series. 



11. The principal modifications which the external conditions 

 of existence of organisms had to undergo, consisted, undoubtedly, 

 in the division of the universal ocean into several seas, Mediter- 

 ranean basins and Caspian lakes, — in the emergence of islands 

 which increased in size, or even united with each other to form 

 continents, — an the elevation of mountain-chains, &c. In paral- 

 lelism with this transformation of the crust of the earth, the 

 organized world presented analogous modifications. The popula- 

 tion of the sea, at first entirely pelagic, became combined with a 

 littoral population, then with a terrestrial but exclusively coast 

 population, and lastly with continental populations, varying with 

 flat and mountainous countries. It is this series of phamomena 



* This, as far as we know, is the first time that these different con- 

 ditions, such as the chemical composition of the air, depressions of the soil, 

 the marshes of Stigmarice, and the formation of coal, have been thus com- 

 bined with each other. This combination seems to us to be equally natural 

 and necessary ; still we admit that this opinion would require to be better 

 supported, aud that it may undergo some modifications. It is still too new 

 to allow us to develope it sufficiently ; perhaps we may do so hereafter. — 

 (Author's note.) 



