78o 



THE POPULAR SCIENCE MONTHLY. 



sarily supposing the complete exclusion of the two others." The reign 

 of Acrogens was manifest during the Carboniferous and Permian peri- 

 ods; the reign of the Gymnosperms during the Vosgian and Jurassic; 

 and the reign of the Angiosperms during the Cretaceous and Tertiary 

 periods. 



Proceeding to the study of the fossil seeds found silicified in the 

 coal-beds of Saint-Etienne, M. Brongniart makes a comparative review 



--CV 



Fig. 2. Cardiocarpus Sclerotesta, Longitudinal Section passing through the Microptle, 

 the Chalaza, and the Principal Plane op the Seed (magnified three times), a, albumen, 

 well preserved, inclosed in the embryonary sac ; b, hardly visible remains of the embryonary 

 sac; c, envelope of the kernel reduced to its epidermis , co, the two corpuscles, placed sym- 

 metrically in the plane of the seed, below the pollinical chamber; m, the pollinical chamber, 

 but slightly developed in this croup of seeds ; rf, endotcsta ; mi, micropylary canal of the 

 testa, leading to the pollinical chamber ; ch, chalazian region of the seed. 



of the structure of the seed and ovule of the cycads, and of different 

 silicified seeds of the coal-beds, and announces one of the most remark- 

 able discoveries in fossil botany, the value of which consists in the 

 light which the study of fossils is made to cast upon the interior 

 anatomy of existing forms. A singular feature was observed in the 

 organization of a considerable number of these seeds, in that there 

 existed, near the summit of the kernel, and in the corresponding part 

 of the micropyle of the testa (or outer integument), a cavity in the 

 cellular tissue, containing nearly always granules or free vesicles, which 

 could only be regarded as grains of pollen ; and from the presence of 

 which M. Brongniart was led to designate the cavity as the pollinical 

 chamber. Nothing of the kind is known in existing gymnosperms. 

 The cycads, however, had been previously indicated as presenting 

 analogies with the Palaeozoic plants under study ; and M. Brongniart's 

 views upon this point have received a striking confirmation from the 

 observations of the gardener of the museum and of M. Renault. The 

 published volume of the " Lectures on Fossil Botany " of the latter 

 gentleman contains a carefully copied plate, showing a similar pol- 

 linical chamber in the Ceratozamia Mcxicana. Figs. 2 and 3 show 

 the grains very plainly in Cardlo carpus sclerotesta. 



