_Alga Zeylanica_; _Ceylon Moss_,[2778] _Jaffna Moss_.
=Botanical Origin=—_Sphærococcus lichenoides_ Agardh. (_Gracillaria
lichenoides_ Grev., _Plocaria candida_ Nees), a light purple or
greenish seaweed, belonging to the class _Florideæ_, occurring on the
coasts of Ceylon, Burma, and the Malay islands.[2779]
=History=—Ceylon moss has long been in use among the inhabitants of the
Indian Archipelago and the Chinese. It is probably one of the plants
described by Rumphius[2780] as _Alga coralloides_. In recent times it
was brought to the notice of European physicians by O’Shaughnessy.[2781]
=Description=—The plant, which as found in commerce is opaque and
white, having been deprived of colour by drying in the sun and air,
consists of cylindrical ramifying stems or filaments, ⅒ of an inch
in diameter and from 1 to 6 or more inches in length. The main stems
bear numerous branches, simple or giving off slender secondary or
tertiary ramifications, ending in a short point. When moistened, the
plant increases a little in volume, becomes rather translucent, and
frequently exhibits whitish globular or mammiform fruits (cystocarps).
It is somewhat friable, and after drying at 100° C. may easily be
powdered. It is devoid of taste and smell, in this respect differing
from most sea weeds.
[2775] Bates in _Amer. Journ. of Pharm._ 1868. 417; also _Pharm.
Journ._ xi. (1869) and viii. (1877) 304.
[2776] A person must eat a _pound_ of stiff jelly made of the powdered
seaweed before he would have swallowed _half an ounce_ of dry solid
matter.
[2777] Fig. in Luerssen (quoted at p. 734) 126.
[2778] For convenience we accept the popular name of _moss_, though it
is no longer in accordance with the signification of the word in modern
science (see p. 737, note 2).
[2779] The _Pharmacopœia of India_ (1868) names _Sphærococcus
confervoides_ Ag. (_Gracillaria_ Grev.), a plant of the Atlantic Ocean
and Mediterranean, not uncommon on the shores of Britain, as furnishing
a portion of the drug under notice. Specimens which we have examined
are widely different in structure from _S. lichenoides_, and are
apparently devoid of starch.
[2780] _Herb. Amboin._ vi. lib. xi c. 56.
[2781] _Indian Journ. of Med. Science_, Calcutta, March, 1834; _Bengal
Dispensatory_, 1841. 668.
=Microscopic Structure=—The transverse section shows a loose tissue
made up of large empty cells, enclosed by a cortical zone 30 to 70
mkm. thick. This zone consists of small cells, loaded with globular
starch granules, from less than 1 up to 3 mkm. in diameter, so densely
packed as to form what seems at first sight a single mass in each cell.
In the larger cells the granules are attached to the walls; they do
not display in polarized light the usual cross. The thick walls of
the cells show a stratified structure, especially after having been
moistened with chromic acid; on addition of a solution of iodine in an
alkaline iodide, they assume a deep brown, but the starch granules,
which also abound in the cystocarps, display the usual blue tint.
=Chemical Composition=—The drug, as examined by O’Shaughnessy, yielded
in 100 parts of vegetable jelly 54·5, starch 15·0, ligneous fibre
(cellulose?) 18·0, mucilage 4·0, inorganic salts 7·5.
Cold water removes the mucilage, which, after due concentration, may
be precipitated by neutral acetate of lead. This mucilage, when boiled
for some time with nitric acid, produces oxalic acid and microscopic
crystals of mucic acid (beautifully seen by polarized light), soluble
in boiling water and precipitating on cooling. With one part of
the drug and 100 parts of boiling water a thick liquid is obtained
which affords transparent precipitates with neutral acetate of lead
or alcohol, in the same way as carrageen. With 50 parts of water, a
transparent tasteless jelly, devoid of viscosity, is produced; in
common with the mucilage, it furnishes mucic acid, if treated with
nitric acid. Micro-chemical tests do not manifest albuminous matter in
this plant.
Some chemists have regarded the jelly extracted by boiling water as
identical with pectin, but the fact requires proof. Payen[2782] called
it _Gelose_, and found it composed of carbon 42·77, hydrogen 5·77,
and oxygen 51·45 per cent. Gum Arabic contains carbon 42·12, hydrogen
6·41, and oxygen 51·47 = C₁₂H₂₂O₁₁. Payen’s gelose imparts a gelatinous
consistence to 500 parts of water; it is extracted by boiling
water from the plant previously exhausted by cold water slightly
acidulated.[2783]
The inorganic salts of Ceylon moss consist, according to O’Shaughnessy,
of sulphates, phosphates, and chlorides of sodium and calcium, with
neither iodide nor bromide. Dried at 100° C., it yielded us 9·15 per
cent. of ash.
=Uses=—A decoction of Ceylon moss made palatable by sugar and
aromatics, has been recommended as a demulcent, and a light article
of food for invalids. In the Indian Archipelago and in China, immense
quantities of this and of some other species of seaweed[2784] are used
for making jelly and for other purposes.
[2782] _Comptes Rendus_, xlix. (1859) 521; _Pharm. Journ._ i. (1860)
470. 508.
[2783] Gelose even in the moist state is but little prone to change,
and the jelly made by the Chinese as a sweetmeat which consists mainly
of it, will keep good for years.
[2784] Consult Martius, _Neues Jahrb. f. Pharm._ Bd. ix. März 1858;
Cooke, _Pharm. Journ._ i. (1860) 504; Holmes, _Pharm. Journ._ ix.
(1878) 45.