Transverse Sections of Carboniferous Wood. 361 
very much, and, in a great measure, depends on the strata 
in which it is embedded. In many cases the wood is so 
completely carbonised as to show little or no evidence of 
cellular structure. Where the plant has undergone a 
process of mineralisation, usually with carbonate of calcium 
or silica, the structure is generally more or less preserved. 
To a certain extent pressure has often taken place, but even 
then the species of the plant to which the wood belonged 
can generally be recognised when thin slices are examined 
with the microscope. 
In this specimen of Araucaroxylon Withami, from the 
Calciferous Sandstone Series at Baberton, we have a good 
example of a fossil stem, showing the cellular structure 
of the wood as well preserved as we would find in a section 
prepared from a living plant. 
The interesting feature in connection with the Baberton 
specimen is the manner in which the wood has been 
fossilised. Only the cell-cavities are filled with silica, the 
cell-walls showing no evidence of the mineral, and, to all 
appearance, are merely carbonised. While on the other 
hand the contents of the cells exhibit, under polarised light, 
the characteristic colouring of crystalline quartz. 
Mr Kidston has kindly supplied us with the following 
note on the subject :—“I have looked at the slices of wood 
from the Baberton New Quarry, and find the plant is the 
Araucaroxylon Witham, L. and H. sp. This generic name 
would imply an affinity with the modern Araucaria. Any 
close relationship to the latter genus is, I think, doubtful, 
and as I have elsewhere pointed out, that when we know 
the Araucaroxzylon Brandlingwi, L. and H. sp., to be the 
wood of Cordaites, the probability is, that the other 
members of the genus <Avraucaroxylon may have the 
same relationship. There is the further indirect evidence 
pointing in the same direction, viz., that no remains, either 
of foliage or fruit, of any coniferous plant has ever, in this 
country, been found in the rocks which have yielded many 
stems of A. Withami, whereas, on the other hand, the same 
horizon has yielded Cordaites remains.” 
1 Grand’ Eury, Flore carbon. du Départ. de la Loire, 1877, p. 257 et seq. 
