The Foot-prints of the Creator : $b or, The Asterolepis of Stromness
John Stuart Mill · en
In the first place, then, this ancient fossil is a true wood,—a
Dicotyledonous or Polycotyledonous _Gymnosperm_, that, like the pines
and larches of our existing forests, bore naked seeds, which, in their
state of germination, developed either double lobes to shelter the embryo
within, or shot out a fringe of verticillate spikes, which performed
the same protective functions, and that, as it increased in bulk year
after year, received its accessions of growth in outside layers. In
the transverse section the cells bear the reticulated appearance which
distinguish the coniferæ, (fig. 58, _a_;) the lignite had been exposed
in its bed to a considerable degree of pressure; and so the openings
somewhat resemble the meshes of a net that has been drawn a little awry;
but no general obliteration of their original character has taken place,
save in minute patches, where they have been injured by compression or
the bituminizing process. All the tubes indicated by the openings are, as
in recent coniferæ, of nearly the same size; and though, as in many of
the more ancient lignites, there are no indications of annual rings, the
direction of the medullary rays is distinctly traceable. The longitudinal
sections are rather less distinct than the transverse one; in the section
parallel to the radius of the stem or bole the circular disks of the
coniferæ were at first not at all detected; and, as since shown by a
very fine microscope, they appear simply as double and triple lines of
undefined dots, (_b_,) that somewhat resemble the stippled markings
of the miniature painter; nor are the openings of the medullary rays
frequent in the tangental section (_i. e._ that parallel to the bark,)
(_c_;) but nothing can be better defined than the peculiar arrangement
of the woody fibre, and the longitudinal form of the cells. Such is the
character of this, the most ancient of lignites yet found, that yields
to the microscope the peculiarities of its original structure. We find
in it an unfallen _Adam_,—not a half-developed savage.[33]
[Illustration: Fig. 58.
INTERNAL STRUCTURE OF LIGNITE OF LOWER OLD RED SANDSTONE.
a. _Transverse section._
b. _Longitudinal section, (parallel to radius, or medullary rays.)_
c. _Longitudinal section, (tangental, or parallel to the bark.)_
(Mag. forty diameters.)]