On Different States of Fossil Vegetables. 103 
it, and the tissues no longer continue to be regular; but itis 
almost always easy to make allowance for these alterations, 
and do away with their effect. 
We perceive that, before endeavouring to compare a fossil 
vegetable with living vegetables, it is necessary,— 
1st, To reconstruct, as completely as possible, according 
to the parts preserved, and the general data of vegetable 
anatomy and organography, the portions of the plant under 
examination. 
2dly, To endeavour to determine what may have been the 
relations of these portions of the plant with the other organs 
of the same plant, searching more especially for their points 
of attachment, their forms and vascular connections ; trying, 
in general, to be guided by the traces of structure rather 
than by the exterior forms. 
3dly, To use every exertion to recomplete a vegetable, by 
seeing whether—among the fossils of the same formation, 
and particularly of the same beds and the same locality— 
there may not be some which belong to the same plant. As 
long as we have not positively ascertained the connection of 
these different organs, we ought not to consider their reunion 
to form the same plant as anything more than a simple pro- 
bability, which positive facts may either overthrow or confirm 
This connection of the different parts of the same plant is 
one of the most important problems to be solved in vege- 
table paleontology, and which must be recommended to the 
special attention of those observers who can engage in the 
inquiry on the spots where these fossils are found. 
M. Brongniart’s Tableaux des Vegetaux Fossiles, from which 
the preceding observations are taken, is divided into two 
principal parts. In the first he explains systematically the 
division of fossils into families and genera. He divides 
them into many branches, comprehending,— 
1st, Amphigenous cryptogamous vegetables, or cellular 
Cryptogams, which he subdivides into two classes,—the 
Fungi and Alge. 
2d, Acrogenous cryptogamous vegetables, comprehending 
two classes, the Musci a numerous class of Filices, itself 
subdivided into five families,—the Ferns, Marsileacee, Cha- 
racer, Lycopodiacee, and Equisetacez. 
