4 THE MEDALS OF CREATION. Cuap. IV. 
be displayed in a distinct and beautiful manner. In calca- 
reous fossil wood the structure is also retained ; and in many 
limestones, leaves and seed-vessels are well preserved. 
The ligneous coverings, or the husks and shells, of nuci- 
ferous fruits, and the cones or strobili of Firs and Pines, are — 
frequently met with in an excellent state of preservation ; 
in some rare instances indications of flowers have been 
observed (Lign. 67). The parts of fructification in some — 
of the fern tribe (Lign. 25 and 27), occur in coal-shale, and — 
in the grit of Tilgate Forest (Wond. p. 394).: the pollen, 
and the resinous secretions of pines and firs, have been dis- — 
covered in tertiary marls, and in the Greensand. ‘The well- 
known substance, Amber, so much in request for ornaments, — 
is unquestionably of vegetable origin; it has been found — 
impacted in the trunks of its parent trees (Wond. p. 242). — 
The fossil resin discovered in the London clay, at Highgate 
and the Isle of Sheppey, is doubtless note to the coni- 
feree found in that deposit. 
In the Clathrariz of Tilgate Forest, indications of a resin- 
ous secretion have been detected. 
The Diamond, which is pure charcoal, is probably a vege- 
table secretion, that has acquired a crystalline structure by 
electro-chemical forces. It has been converted into Coke — 
and Graphite by the action of intense heat; and the elec- 
trical properties of the substance were changed, the Diamond 
being an insulator, and the Coke, a conductor of electricity. 
(Wond. p. 706.) 
When the microscope is more extensively employed in 
investigations of this kind, it is probable that the siliceous 
spines a stars which begem the foliage of many plants 
(as the Deutzia, Lithospermum officinale, &c.), will be dis- 
covered in a fossil state, for they are as indestructible as 
the frustules of Diatomacez, and the spicules of sponges 
which are so common in flint and chalcedony. 
But vegetables occur not only as petrified stems, leaves, 
