242 Professor Dyer — On some Eocene Fossil Wood. 



of long prosenchymatous fibrous cells. Adjacent, however, to the 

 ducts there are often found in the wood of plants cells of what has 

 been termed wood-parenchyma, which are shorter and less obliquely 

 truncated than the prosenchymatous wood-cells, and are also con- 

 spicuously marked with pores corresponding to those seen on the 

 walls of the duct. This wood-parenchyma is clearly shown in Fig. 6, 

 on the right hand side of the figure, which is drawn from the Vine 

 for the sake of comparison. In the Thanet fossil wood the vessels 

 were also surrounded by short-celled wood-parenchyma, the walls of 

 which were marked by large slit-like pores, which stretched in a 

 somewhat scalariform manner across each face of the cells. This is 

 the explanation of the slit-like markings to be seen amongst the 

 wood-cells in Fig. 2 ; the artist has drawn the specimen faithfully as 

 he saw it, and the markings were more distinguishable in this 

 particular specimen than the cells to which they belonged. The 

 smaller circular bodies delineated amongst or rather in the wood- 

 cells in the same figure represent, I think, not improbably starch 

 granules. It only occurred to me after I had arrived at this con- 

 clusion, that Mr. Carruthers had ascertained that the form and 

 arrangement of starch granules in the cells was also admirably 

 preserved in the stem of a fossil fern, Osmundites Dowkeri, from the 

 same locality and geological horizon.^ 



The most curious feature about this wood is, however, the cellular 

 mass (Tylose) with which the interior of the ducts is filled up ; this 

 is shown very characteristically in Fig. 2. Dr. Bowerbank made 

 this anomalous structure the subject of a paper in the first volume 

 of the Transactions of the Microscopical Society of London.^ The 

 material upon which he worked was a fossil wood from the London 

 Clay, which appears from its structure to have been identical with 

 that from Heme Bay. In both cases the included vesicles vary in 

 size, being often, as in Fig. 3, small and not so large as to compress 

 one another. His conclusion was, that " it appears probable that 

 the whole of them may be attributed to a more than ordinary 

 development of the globules of circulation, analogous to those 

 observed in Vallisneria and other plants." 



Dr. Arthur Farre, in a subsequent paper in the same volume, fol- 

 lowed up Dr. Bowerbank's view as to the origination of these vesicular 

 bodies from the contents of the duct, but thought that they might 

 have originated by a process of " balling " similar to that by which 

 the endochrome of Nitella, when it begins to decay, breaks up into 

 globular masses with a brownish investment. He remarks with 

 judicious caution that " these brown globules contained in the stems 

 of Nitella, appear to difi"er from the globules found in the vessels of the 

 fossil wood chiefly in the circumstance of their being hollow spheres 



^ Quart. Journ. Geol. Soc, vol. xxvi., pi. xxv. Amylaceous structure is also shown 

 in the Fern-structures described by Renault, from Autun (Carboniferous), Ann. d. So. 

 Nat., 1869. 



2 On a New Variety of Vascular Tissue found in a Fossil Wood from the London 

 Clay, pp. 16-18. (1844.) 



