les, X500.]

From what precedes it seems to result, then, that anthracite is in a much
less appreciable state of preservation than cannel coal, and that it is
only rarely, and according to locality, that we can discover vegetable
organs in it. Soft coal comes nearer to amorphous carbon. Boghead appears
to be of an entirely different character (Fig. 5, magnified X300). It is
easily reduced to a thin transparent plate, and shows itself to be formed
of a multitude of very small lenses, differing in size and shape, and much
more transparent than the bands that separate them. In the interior of
these lenses we distinguish very fine lines radiating from the center and
afterward branching several times. The ramifications are lost in the
periphery amid fine granulations that resemble spores. We might say that
we here had to do with numerous mycelia moulded in a slightly colored
resin. Preparations made from New South Wales and Autun boghead presented
the same aspect.

If boghead was derived from the carbonization of parts that were soluble,
or that became so through maceration, and were made insoluble at a given
moment by carbonization, we can understand the very peculiar aspect that
this combustible presents when it is seen under the microscope.

The following figures were made in order to show the details of anatomical
structure that are still visible in coal, and to permit of estimating the
shrinkage that the organic substance has undergone in becoming converted
into coal.

It is not rare in coal mines to find fragments of wood, of which a portion
has been preserved by carbonates of iron and lime, and another portion
converted into coal. This being the case, it was considered of interest to
ascertain whether the carbonized portion had preserved a structure that
was still recognizable, and, in such an event, to compare this structure
with that of the portion of the specimen that was preserved in all its
details by mineralization.

[Illustration: 12f: FIG. 6.--_Arthropitus gallica_, St. Etienne; transverse
section, X200.]

Fig. 6 shows a transverse section of a specimen of _Arthropitus Gallica_
found under such conditions. The region marked c is carbonized; the
organic elements of the wood-cells, tracheae, etc., have undergone but
little change in shape. Moreover, no change at all exists in the
internal parts of another specimen (Fig. 8), where we easily distinguish
by their form and dimensions the ligneous cells, _aa_,