ILLUSTRATED BY FIGURES. 91 
I. AGAMIC PLANTS. 
These plants have an organization consisting entirely of cellular tissue, 
or intersecting tubular filaments, without vessels; are entirely destitute of 
leaves, and have only, as organs of reproduction, very minute seminula, 
which appear to be developed without fecundation, and which are contained 
immediately in membranous conceptacles, similar to the filaments or cellules 
of the general tissue of the plants. 
To this class belong the Algw, Fungi, and Lichens. 
II. CELLULAR CRYPTOGAMIC PLANTS. 
The plants of this class have an entirely cellular organization, but they 
possess leaves having a structure and functions similar to those of the more 
perfect vegetables. 'There are sexual organs, and the seminula are con- 
tained in conceptacles of a very complex organization. 
This class contains the Hepatice and Muscv. 
III. VASCULAR CRYPTOGAMIC PLANTS, 
The cellular tissue, which is diversiform, almost always contains distinct 
vessels, most commonly trachez or false trachee; the leaves are highly de- 
veloped, and furnished with cortical pores; the stems are often very large 
and arborescent, bearing some resemblance in their structure to those of the 
monocotyledones; and the organs of reproduction appear always to consist 
of two distinct sexes, which produce seminula contained in conceptacles of 
somewhat complicated organization. 
This class contains the Equisetacee, Filices, Lycopodiacee, Marsi- 
liacece, and Characee. 
IV. GYMNOSPERMOUS PHANEROGAMIC PLANTS. 
To this class belong the very remarkable families of Cycadew and Co- 
nifere, which cannot be referred to any of the other classes, as their seeds, 
