FOSSIL SEEDS. 



779 



Before entering upon the account of his studies, Brongniart de- 

 scribes, in an introductory chapter, the periods of vegetation and the 

 different floras that have succeeded each other on the earth's surface. 

 " We may consider," he says, " as having been deposited during a same 

 epoch of the creation of the vegetable kingdom, and as belonging to 



Fig. 1 Specimens op Fossil Seeds examined by Adolphe Brongniart. 1, Cardiocarpus 

 drupaceus. Section through the plane of the keel, a, thick teeta ; 6, chalaza ; c, kernel 

 and albumen ; d, micropylar extremity of the kernel (natural size). 2, Rhabdocarpus conicus. 

 Grand' Eury. General form from a specimen that was broken before preparation (natural 

 size). 3, Trigonocarjms pusilits (natural size). 4, longitudinal section passing through the cha- 

 laza and the micropyle (magnified five times) ; a, testa ; b, chalaza : c. micropyle ; d, kernel; 

 e, cavity on the summit of the kernel, with grains of pollen. 5, Poly pterosper mum Renault/i, 

 transverse section (natural size). 6. Codonospermum anomolum, external view, as it appears 

 in the broken rock. 



a same ancient flora, the different beds in which we find the same 

 collection of species, and during the deposition of which some at least 

 of these species have persisted from the beginning to the end of the 

 local phenomena. 



" This is what constitutes an epoch in the geological study of vege- 

 table fossils ; but several of these epochs often succeed one another, 

 all preserving a considerable number of common characters in the 

 nature and relative proportion of the principal families that belong to 

 them ; and this succession of analogous epochs forms a period in the 

 history of the successive development of the vegetable kingdom." 



The successive creation of different vegetable forms is thus divided 

 into three long periods, called the reign of the Acrogens, the reign 

 of the Gymnosperms, and the reign of the Angiosperms "expres- 

 sions indicating only the successive jiredominance of one or another of 

 these three grand divisions of the vegetable kingdom, without neces- 



