The internal structure of fossil vegetables found in the carboniferous and oolitic deposits of Great Britain. Described and illustrated / By Henry T.M. Witham.

  • Witham, Henry T. M. (Henry Thornton Maire)
Date:
1833
Catalogue details

Licence: Public Domain Mark

Credit: The internal structure of fossil vegetables found in the carboniferous and oolitic deposits of Great Britain. Described and illustrated / By Henry T.M. Witham. Source: Wellcome Collection.

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    from the fragment of the stem. The latter has been sliced, and shews the concentric rings in a perfection almost approaching to the fossils of the Lias. Fig. 5. represents a thin transverse slice, viewed by transmitted light, and of the natural size. The pith is seen to be very large, and there are decided indications of five concentric layers. Fig. 6. represents the pith highly magnified. Besides the large aper- tures of the circular cells, there are others of much smaller size, presenting somewhat of the appearance of vessels. Fig. 7. represents a portion of a transverse slice, in which are seen the margin of the pith, several medullary rays proceeding from it, and the ordi- nary reticulated appearance of the elongated cellules. Fig. 8. represents the breadth of the two inner woody layers, with part of the third. The lines of separation are distinct; and the medullary rays, together with the series of cellules, are flexuous, probably from accidental distortion. The texture is much better preserved, in the branch of which the above figures are representations, than in either of the great stems; but in all it is similar. The analysis of the fragment and branch is as follows :— Lime, 37.5 Peroxide of Iron, . . ■ . • . 24.2 Coal, 38.1 99.8 It is singular that the composition of these stems should differ so much from that of the enclosing rock. When we find in beds of sandstone and shale, vegetable trunks transmuted into substances of a similar nature, the presence of the sand or mud, and the decay of the vegetable matter, afford an easy explanation of the manner in which the transmutation has been ef- fected ; but when the petrifying substance is different in nature from that forming the matrix of the fossil, difficulties occur. Yet, if we take the whole mass or group of substances constituting a formation, we may find