V 



oublier toutes, a reunir des faits bien observes, a deduire de leur com- 

 paraison des conclusions de detail, et a former du rapprochement de 

 celles-ci une theorie propre a les representer." 



Brongniart showed bow the embryo is formed, little by little, by a 

 process which he did not hesitate to say is identical over the whole 

 of the vegetable kingdom. Microscopically small plants, the most 

 majestic trees of onr forests, onr cultivated plants, all are reproduced 

 by one and the same process. 



For some years Brongniart prosecuted his investigations of living 

 plants, and published, between 1824 and 1827, a new classification of 

 fungi, a memoir on the natural order Bruniaceae, and several histo- 

 logical and physiological memoirs. The labours and observations of 

 six years in Palaeontology were exhibited in his "Prodrome d'une 

 Histoire des Vegetans Fossiles," puplished in 1828, and in his great 

 work, " Histoire des Vegetans Fossiles," begun in the same year. 

 The first volume, consisting of twelve parts, and containing 488 pages 

 of letter-press and 160 quarto plates, was issued within a few months. 

 The further progress of the work was interrupted by Brongniart's ill 

 health, and it was not resumed for nine years, and then only three 

 additional parts were issued, leaving this great work incomplete. The 

 "Histoire" includes the whole of the Cryptogams, vascular as well as 

 cellular, with the exception of the Lycopodiaceee, to which the later 

 plates are devoted ; and the letter-press is suddenly stopped before the 

 remarkable introduction to this natural order was completed. 



In 1839 he brought out his well-known memoir on Sigillaria elegans. 

 In 1849 he contributed to the " Dictionnaire TJniversel d'Histoire 

 ISTaturelle," a short and popular review of fossil plants on the plan of 

 his " Prodrome," exhibiting their botanical affinities and classification 

 and their stratigraphical distribution. 



It is worthy of notice that, as Brongniart began his scientific 

 career with his labours on fossil plants, so the latter part of his life 

 was devoted to a further investigation on the same subject. At the 

 time of his first investigation only few and imperfect specimens had 

 been obtained. Fifty years later his friends, Messieurs Renault and 

 Grand d'Eury, sent him, from the environs of Autun and St. Etienne, 

 a quantity of specimens of seeds which had been converted into 

 siliceous masses of a texture as fine as that of the most beautiful agates. 

 From these masses Brongniart separated transparent flakes, and, by 

 the aid of the microscope, made out minute details of their organiza- 

 tion, cells with excessively thin walls, vessels with delicate membranes, 

 nebulosities which are the first indications of the formation of tissues, 

 organisms, in fact, of dimensions so small as can only be detected by 

 high powers of the microscope. He found, in fruits dating from 

 remote ages, all the particulars of organization which he had formerly 

 observed in living plants. JSTo one had hitherto imagined it possible 



