262 
ORGANOGRAPHY. 
BOOK I. 
their functions. Such is my view of the structure of Ophio- 
glossaceas ; but by other botanists it is described as a dense 
spike of two-valved capsules, dehiscing transversely. 
2. Equisetacece. 
In these plants, which may, I think, be as properly con- 
sidered the lowest form of flowering plants, the stem is hollow, 
jointed, and bears a toothed sheath at each joint. The 
cylinder of the stem is pierced by longitudinal fistulas, which 
alternate with furrows on the outside of the stem ; there is 
also a bundle of ringed vessels connected with the fistulas. 
The organs of reproduction are arranged in a cone, con- 
sisting of scales bearing on their lower surface an assem- 
blage of cases, called sporangia, theccB, folliculi, or involucra, 
which dehisce longitudinally inwards. In these sporangia 
are contained two sorts of granules ; the one very minute 
and lying irregularly among a larger kind, wrapped in 
two filaments, fixed by their middle, rolled spirally, having 
either extremity thickened, and uncoiling with elasticity. 
By Hedwig the apex of the larger granules was supposed to 
be a stigma, and the thickened ends of the filament anthers, 
the small granules being the pollen. It is certain that the 
larger granules, round which the elastic filaments are coiled, 
are the reproductive particles; and it seems to me that they 
may be compared to the naked seeds of Coniferae, the only 
order to which Equisetaceae appear to have much resemblance ; 
but Mr. Grififith differs from me upon this point. This 
excellent observer states that the club-shaped bodies which 
Hedwig referred to stamens are elaters, and are developed in 
or on a loose membranous coat, and later than the central 
body, spore, or seed. 
3. Lycopodiacece. 
These are leafy plants with the habit of gigantic mosses. 
Their leaves and stem have the same structure as those 
plants, except that the former are sometimes provided with 
stomates, and the latter with a central bundle of vessels. 
