porangia 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 should have stopped in that position if they had got
there.

At the same time, it is proper to remark that I do not presume to
suggest that all coal must needs have the same structure; or that
there may not be coals in which the proportions of wood and spores, or
spore-cases, are very diffe