idered an effectual remedy in any disorder where
pure bitters are required. Surinam quassia is not, however, to be met
with now. That sold in the shops is the tough, fibrous, bitter bark of
the root of _Simaruba (Quassia) excelsa_ and _officinalis_, very large
forest trees, growing in Cayenne, Jamaica, and other parts of the West
India Islands, where they bear the local name of bitter-wood. Its
infusion is used as a tonic. 23 tons of bitter-wood were shipped from
Montego Bay, Jamaica, in 1851. Quassia acts as a narcotic poison on
flies and other insects. Although prohibited by law, it is frequently
employed by brewers as a substitute for hops. The duty of L8 17s. 6d.
per cwt., levied on quassia, is intended to restrict its use for such
a purpose.

Rhubarb.--This most important plant belongs to the genus Rheum. The
officinal rhubarb is the root of an undetermined species. There are
about thirteen different kinds which are said to yield rhubarb.
Lindley enumerates fifteen. I however take Professor Balfour's
classification:--

1. _Rheum palmatum_, native of Bucharia, which has perhaps the best
title to be considered the true rhubarb-plant, grows spontaneously
in the Mongolian empire on the confines of China.

2. _R. undulatum_, native of China, which yields much of the French
rhubarb.

3. _R. compactum_, native of Tartary, another species yielding
French rhubarb, and often cultivated in Britain for its acid
petioles.

4. _R. Emodi_ (Wallich). This species yields a kind of Himalayan
rhubarb. Its petioles are much used for their acid properties.

5. _R. Rhaponticum_, native of Asia. Used in France and Britain in
the same way as the third species. It is much cultivated in the
department of Morbihan.

6. _R. hybridum_ (Murr). Much cultivated in Germany for its root and
in Britain for its stalks.

7. _R. Webbianum_ (Royle). 8. _R. Spiceformi_ (Royle). 9. _R.
Moorcroftianum_ (Royle). Himalayan species or varieties.

10. _R. crassinervium_ (Fisch), a Russian species.

11. _R. leucorhizum_ (Pall), a Siberian and Altai species, said to
yield imperial or white rhubarb. It has striped flowers, while all
others are whitish green.

12. _R. Caspicum_ (Fisch), a Russian and Altai species.

13. _R. Ribes_, native of the Levant, but some say an Afghanistan or
Persian species.

All these grow in the cold parts of the world, as on