INVESTIGATION OF TEMPERATURE CHANGES. 251 



G. de Saporta has given a comprehensive review of the indications fur- 

 nished by fossil pLmts in regard to the climates of the past geological ages. 

 The present writer thinks it proper to furnish here a brief abstract of the 

 results reached by this eminent authority in fossil botany, which results will 

 be found to be entirely corroborative of those advanced in the preceding 

 pages, and to harmonize, in almost every particular, with the views of Heer 

 and Lesquereux.* 



Saporta first considers the plants of the Carboniferous epoch Referring 

 to the investigation of Messrs. Grand' Eury and B. Renault on the vegetation 

 of that period, he says : " Both agree in recognizing the abnormal habit 

 [allures desordonnees] the continuous budding [pousses] prolonged until the 

 stem has become exhausted, and the absence, in fact, of all indications of 

 regular, periodic growth, among the plants which characterize the Carbon- 

 iferous flora. Thus, it seems that not only was the heat of that period 

 extreme ; but, according to all appearances, it was not limited by any peri- 

 odically returning intervals, comparable with those which characterize our 

 seasons." t 



From this point of departure Saporta goes on to show that a seasonal 

 regimen of climate gradually and slowly became established. At a period 

 later than the Carboniferous — the Cretaceous, as already mentioned — the 

 trunks of coniferous trees, with regular concentric rings of gi'owth, bear wit- 

 ness to the existence of seasons, although as yet by no means well marked, 

 as is proved by the presence at the same time of abundant cycads and arbo- 

 rescent ferns, which during that epoch were spread over a large part of 

 Europe and extended to regions beyond the polar circle. Thus, as it appears 

 evident to Saporta, it was not until after the beginning of the Cretaceous 

 that the first traces of a differentiation between the climates of the Arctic 

 region and of Central Europe began to show themselves. 



Passing over the remarks made by the author from whose work we are 

 quoting, about the fossil plants of the formations intermediate between the 

 Carboniferous and the Tertiary in Central Europe, we arrive at his conclu- 

 sions in regard to the later geological periods. He thus states his views: 

 "For the sake of brevity, we will start from the Eocene. Palms are at that 



* The resumi by Saporta from which these extracts have been taken is to be found in the Revue des Deux 

 Moudes, in the numbers for September 15 and October 15, 1881, (Troisieme Periode, Tome XLVII. pp. 335-369 

 and 835 - 866,) under the head of " Les Temps Quaternairea. " 



t 1. c, p. 358. 



