, very closely resemble true mosses, and none
of them reach more than two or three feet in height. But, in their
essential structure, they very closely resemble the earliest
Lepidodendroid trees of the coal: their stems and leaves are similar; so
are their cones; and no less like are the sporangia and spores; while
even in their size, the spores of the _Lepidodendron_ and those of the
existing _Lycopodium_, or club-moss, very closely approach one another.

Thus, the singular conclusion is forced upon us, that the greater and the
smaller sacs of the "Better-Bed" and other coals, in which the primitive
structure is well preserved, are simply the sporangia and spores of
certain plants, many of which were closely allied to the existing club-
mosses. And if, as I believe, it can be demonstrated that ordinary coal
is nothing but "saccular" coal which has undergone a certain amount of
that alteration which, if continued, would convert it into anthracite;
then, the conclusion is obvious, that the great mass of the coal we burn
is the result of the accumulation of the spores and spore-cases of
plants, other parts of which have furnished the carbonized stems and the
mineral charcoal, or have left their impressions on the surfaces of the
layer.

Of the multitudinous speculations which, at various times, have been
entertained respecting the origin and mode of formation of coal, several
appear to be negatived, and put out of court, by the structural facts the
significance of which I have endeavoured to explain. These facts, for
example, do not permit us to suppose that coal is an accumulation of
peaty matter, as some have held.

Again, the late Professor Quekett was one of the first observers who gave
a correct description of what I have termed the "saccular" structure of
coal; and, rightly perceiving that this structure was something quite
different from that of any known plant, he imagined that it proceeded
from some extinct vegetable organism which was peculiarly abundant
amongst the coal-forming plants. But this explanation is at once shown to
be untenable when the smaller and the larger sacs are proved to be spores
or sporangia.

Some, once more, have imagined that coal was of submarine origin; and
though the notion is amply and easily refuted by other considerations, it
may be worth while to remark, that it is impossible to comprehend how a
mass of light and resinous spores should have reached the bottom of the
sea, or sho