_Cortex Swieteniæ_; _Rohun Bark_.
=Botanical Origin=—_Soymida[637] febrifuga_ Juss. (_Swietenia
febrifuga_ Willd.), a tree of considerable size not uncommon in the
forests of Central and Southern India. The timber called by Europeans
_Bastard Cedar_ is very durable and strong, and much valued for
building purposes.
=History=—The introduction of Rohun Bark into the medical practice
of Europeans is due to Roxburgh[638] who recommended the drug as a
substitute for Cinchona, after numerous trials made in India about the
year 1791. At the same time he sent supplies to Edinburgh, where Duncan
made it the subject of a thesis[639] which probably led to it being
introduced into the materia medica of the Edinburgh Pharmacopœia of
1803, and of the Dublin Pharmacopœia of 1807.
Though thus officially recognized, it does not appear that the bark
came much into use or by any other means fulfilled the expectations
raised in its favour. At present it is regarded simply as a useful
astringent tonic, and as such it has a place in the _Pharmacopœia of
India_ (1868).
=Description=—Our specimen of Rohun bark[640] which is from a young
tree, is in straight or somewhat curved, half-tubular quills, an inch
or more in diameter and about ⅕ of an inch in thickness. Externally
it is of a rusty grey or brown, with a smoothish surface exhibiting
no considerable furrows or cracks, but numerous small corky warts.
These form little elliptic scars or rings, brown in the centre and
but slightly raised from the surface. The inner side and edges of the
quills are of a bright reddish colour.
A transverse section exhibits a thin outer layer coloured by
chlorophyll, and a middle layer of a bright rusty hue, traversed by
large medullary rays and darker wedge-shaped rays of liber. The latter
has a fibrous fracture, that of the outer part of the bark being
rather corky or foliaceous. The whole bark when comminuted is of a
rusty colour, becoming reddish by exposure to air and moisture. It has
a bitter astringent taste with no distinctive odour. The older bark
frequently half an inch thick and fibrous, has a thick ragged corky
layer of a rusty blackish-brown colour, deeply fissured longitudinally,
and minutely cracked transversely. Old bark, according to Dymock
(1877), is generally in half quills of a rich red-brown colour.
=Microscopic Structure=—The bark presents but few structural
peculiarities. The ring of liber is made up of alternating
prosenchymatous and parenchymatous tissue. In the latter the
larger cells are filled with mucilage, the others with starch. The
prosenchymatous groups of the liber exhibit that peculiar form we have
already described as _hornbast_ (p. 74); it chiefly contains the tannic
matter, besides stellate crystals of oxalate of calcium which are
distributed through the whole tissue of the bark. The medullary rays
are of the usual form, and contain starch granules. The corky coat is
built up of a smaller number of vaulted cells.
[637] From _Sómida_, the Teluga name of the tree; _Róhan_ is its name
in Hindustani.—Fig. in Bentley and Trimen, _Med. Plants_, part 18
(1877).—See also C. De Candolle, in _Monogr. Phanerogamar._ i. (1878)
722.
[638] _Medical Facts and Observations_, Lond. vi. (1795) 127.
[639] _Tentamen inaugurale de Swieteniâ Soymidâ_, Edinb. 1794.
[640] Kindly sent us by Mr. Broughton of Ootacamund.
=Chemical Composition=[641]—The bitter principle of the bark has been
ascertained by Broughton[642] to be a nearly colourless resinous
substance, sparingly soluble in water but more so in alcohol, ether, or
benzol. It does not appear to unite with acids or bases, and is less
soluble in water containing them than in pure water. It has a very
bitter taste, and refuses to crystallize either from benzol or ether.
It contains no nitrogen. To this we may add that the bark is rich in
tannic acid.
=Uses=—Rohun bark is administered in India as an astringent tonic
and antiperiodic, and is reported useful in intermittent fevers and
general debility, as well as in the advanced stages of dysentery and in
diarrhœa.