42 THE ESSEX NATURALIST.
of Walnut, the wood has an extremely even texture, and has very
numerous and minute vessels. No attempt has been made
here to describe any of these woods in detail : it has simply
been shown how a few points may serve to distinguish one
timber from another with the help of nothing but a sharp pen-
knife and a pocket lens.
Ebony. Finally mention may be made of Ebony and its
substitutes. Ebony is the wood of trees of the genus Diospyros,
members of the Ebenaceae. The wood is hard and compact,
and is in demand for the manufacture of small articles—brash-
backs, trinket sets, and so forth, apart from its use for decorative
work. It is usually treated to darken it, producing a wood of
a jet-black colour. It has many substitutes ; any wood of a
hard even texture, when treated to give it a black colour, will
have an appearance approximating to that of ebony. Common
substitutes are Holly (Ilex Aquifolium). Hornbeam (Carpinus
Betulus) and Pear (Pyrus communis), which is sometimes called
German Ebony. In addition there is the African Blackwood
(Dalbergia Melanoxylon), which is extracted with and sold as
ebony. The characteristic features of ebony can be made out
with care with a lens : the end grain shows narrow rays, fairly
numerous vessels and abundant concentric parenchyma. A piece of
Dalbergia will also show small vessels, but these will be surrounded
by parenchyma, and there will be no concentric parenchyma.
In Holly the characteristic features are the angular vessels
united in long radial chains, and the broad rays : Hornbeam
also has somewhat angular vessels, in short radial chains, and
the rays are much thinner than in Holly, although what appear
to be wide rays will also be seen ; examination of a tangential
section under the microscope will at once serve to distinguish
it from Holly, for in Holly the rays are broad, boat-shaped
structures with a conspicuous "tail" at either end, formed by
a single line of cells : in Hornbeam, on the other hand, the
majority of the rays are fairly narrow, about three cells wide,
and the large rays seen on the transverse section are now revealed
as numbers of small rays, separated by fibres, and forming what
is known as an aggregated ray. Pear would be distinguished
by its very numerous and minute vessels and narrow rays.