SAPORTA'S WORLD OF PLANTS. 



457 



sort witnessed the successive appearance of different classes of plants, 

 we have seen the rising and falling movements of vegetation, periods 

 of activity alternating with periods of relative repose, and that succes- 

 sion, or better, that procession of phenomena which has enabled us, if 

 not to comprehend, at least to prove the transformations of life that 

 all together are called evolution. 



We shall find analogous phenomena in the series of Tertiary time, 

 to which Saporta has given his longest chapter. This part of his work 

 contains many descriptions of plants. They show us more than the 

 simple succession of flora. The growing differentiation of the divers 

 types and the consequent multiplication of species conduct us insensi- 

 bly to the actual vegetable world. We see the growth of local flora, 

 some of which are so clearly defined that we are able, by the aid of 

 the imagination and of some well-preserved fragments, to reconstruct 

 the principal genera and species of which they were composed. Fig. 1 

 represents a group of these plants so restored. The numerous modifi- 

 cations undergone by the vegetable kingdom during the Tertiary age, 

 the formation of local floras, etc., are easily explained if we recall 

 what was before said, of the influence of the medium upon living beings, 

 and especially upon plants, that can not escaj^e. Climatic equality no 

 longer exists. The European Continent, up to this time made up of 

 islands, tends now to aggregate and take on its present form ; the soil 



Fig. 7.— HoMOLOooua Forms op Paleocene and Eocene Oaks compared (Tjyes of entire 

 leaves): 1. Quercus Lairiberti (Wat.) (Paleocene). 2. Quercus taniata (Sap.) (Middle Eocene). 

 3. Quercus maciknta (Sap.) (Middle Eocene). 4. Quercu.t paleophellos (Sap.) (Upper Eocene). 

 5. Quercus eUiptica (Upper Eocene). 6. Quercus salicina (Upper Eocene). 



is subject to movements of oscillation, which often change the config- 

 uration and relief of various countries. Lakes of fresh water are 

 formed, and then disappear. The nature of the soil varies as marine 

 deposits recapture it from deposits of fresh water ; and reciprocally. 



