M. Arago''s Historical Eloge of Joseph Fourier. ^97 



plants of the most simple structure : ferns, reeds, and lycopo- 

 diums. 



Vegetation becomes more and more complicated in the upper 

 formations. Finally, near the surface, it resembles the vegeta- 

 tion of the present continents, but with this very remarkable 

 addition, that certain vegetables which flourish only in the south, 

 such as large palm trees for instance, are found, in a fossil 

 state, in all latitudes, and even in the midst of the frozen regions 

 of Siberia. 



In the ancient world, these northern regions must thus have 

 possessed, during winter, a temperature at least equal to that 

 which is experienced at present in the parallels where large 

 palm-trees begin to flourish. At Tobolsk there was the cli- 

 mate of Alicant or Algiers ! 



We shall discover fresh proofs of this mysterious result, 

 from an attentive examination of the dimensions of plants. 



There are, at the present day, species of reeds, of ferns 

 and Lycopodiums, as well in Europe as in the Equinoctial 

 regions ; but it is only in warm climates that they are of great 

 dimensions. Thus, a comparison of the dimensions of the 

 same plants is, in fact, to compare, in reference to temperature, 

 the regions where they were produced. Well, place beside 

 the fossil plants of our coal formation, I do not say the analo- 

 gous European plants, but those which abound in those re- 

 gions of South America, the most celebrated for the richness of 

 their vegetation, and you will find the former incomparably 

 larger than the latter. 



The Jbssil floras of France, England, Germany, and Scan- 

 dinavia exhibit, for instance, ferns nearly fifty feet high, and 

 with branches three feet in diameter, or nine feet in circum- 

 ference. 



The Lycopodinece which, at the present time, in cold or 

 temperate regions, are creeping plants, scarcely rising above 

 the surface ; which, even at the Equator, under the most favour- 

 able circumstances, do not rise to more than three feet, reached 

 in Europe, in the ancient world, to the height of eighty feet. 



One must be blind, not to see, in these enormous dimensions, 

 a new proof of the high temperature formerly possessed by our 

 country, before the last irruptions of the ocean. 



