=Botanical Origin=—The plant which bears this important kind of gall,
is _Rhus semialata_ Murray (_Rh. Bucki-amela_ Roxb.), a tree attaining
30 to 40 feet, common in Northern India, China and Japan, ascending in
the outer Himalaya and the Kasia hills to elevations of 2,500 to 6,000
feet.[683]
=History=—In China these galls are probably known and used both
medicinally and in dyeing since very long; they are mentioned in the
herbal Puntsaou, written in the middle of the 16th century. They also
occur in Cleyer’s “Specimen medicinæ sinicæ,” Frankfort, 1682, No.
225, under the name _u poi çu_.[684] Kämpfer[685] also mentions a tree
“Baibokf, vulgo Fusi,” growing on the hills, the pinnate leaves of
which he found often provided with an excrescence: “Ἐπίϕνσι foliorum
informi, tuberosa, multiplici, tenui, dura, cava, Gallæ nostratis usu
praestante.” No doubt this refers to the galls under notice; they began
to be imported into Europe about 1724, and are noticed by Geoffroy[686]
as _Oreilles des Indes_, but they seem to have soon disappeared from
the market. Pereira directed attention to them in 1844, since which
time they have formed a regular and abundant article of import both
from China and Japan.
[682] From analysis performed in my laboratory by Dr. Kraushaar.—F. A.
F.
[683] Wight, _Icones Plantar. Indiæ orientalis_, ii. (Madras, 1843)
tab. 561, gives a good figure.
[684] Hanbury, _Science Papers_, 266.
[685] _Amœnitates exoticæ_, 1712. 895.
[686] _Mém. de l’Académie royale des Sciences_, Paris, 1724. 324.—Also
Du Halde, _Description de l’Empire de la Chine_, iii. (La Haye, 1736)
615-625. “Des Ou Poey tsé.” The author quotes numerous medicinal
applications for these galls.
=Formation=—Chinese galls are vesicular protuberances formed on the
leafstalks and branches of the above-mentioned tree, by the puncture
of an insect, identified and figured by Doubleday[687] as a species
of _Aphis_, and subsequently named provisionally by Jacob Bell[688]
_A. chinensis_. We have no account by any competent observer of their
growth; and as to their development, we can only imagine it from the
analogous productions seen in Europe. According to Doubleday, it
is probable that the female aphis punctures the upper surface of a
leaf (more probably _leafstalk_), the result of the wound being the
growth of a hollow expansion in the vegetable tissue. Of this cavity
the creature takes possession and brings forth a progeny which lives
by puncturing the inner surface of their home, thus much increasing
the tendency to a morbid expansion of the soft growing tissue in an
outward direction. Meanwhile the neck of the sac-like gall thickens,
the aperture contracts and finally closes, imprisoning all the inmates.
Here they live and multiply until, as in the case of the pistacia
gall of Europe, the sac ruptures and allows of their escape. This, we
may imagine, takes place at the period when, after some generations
all wingless and perhaps all female (for the female aphis produces
for several generations without impregnation), a winged generation is
brought forth of both sexes. These may then fly to other spots, and
deposit eggs for a further propagation of their race.
The galls are collected when their green colour is changing into
yellow; they are then scalded.[689]
=Description=—The galls are light and hollow, varying in length from
1 to 2½ inches, and of extremely diverse and irregular form. The
simplest are somewhat egg-shaped, the smaller end being attached to the
leafstalk; but the form is rarely so regular, and more often the body
of the gall is distorted by numerous knobby or horn-like protuberances
or branches; or the gall consists of several lobes uniting in their
lower part and gradually attenuated to the point by which the
excrescence is attached to the leaf.[690] But though the form is thus
variable, the structure of these bodi4s is very characteristic. They
are striated towards the base, and completely covered on other parts
with a thick, velvety, grey down, which rubbed off on the prominences,
displays the reddish-brown colour of the shell itself. The latter is
⅒ to ¹/₂₀ of an inch in thickness, translucent and horny, but brittle
with a smooth and shining fracture. It is rather smoother on the inner
surface and of lighter colour than on the outer.
[687] _Pharm. Journ._ vii. (1848) 310.
[688] _Ibid._ x. (1851) 128.
[689] Stanisl. Julien et P. Champion, _Industries anc. et modernes de
l’Empire chinois_, 1869. 95.
[690] We have once met with galls imported from Shanghai which
differed from ordinary Chinese galls in not being horned, but all of
an elongated ovoid form, often pointed at the upper end, and having
moreover a strong _cheesy_ smell. They may be derived from _Distylium
racemosum_ S. et Z., though they do not perfectly accord with the
depressed pear-shaped forms figured by Siebold and Zuccarini (_Flora
Japonica_, tab. 94).
The galls when broken are generally found to contain a white,
downy-looking substance, together with the minute, dried-up bodies of
the killed insect.[691]
The drug as imported from Japan is usually a little smaller and paler;
it mostly fetches a better price in the market.
=Microscopic Structure=—The tissue of the galls is made up of
thin-walled, large cells irregularly traversed by small vascular
bundles and laticiferous vessels. The latter are mostly not branched.
The parenchyme is loaded with lumps of tannic matter and starch, the
latter having mostly lost by the treatment with boiling water its
granular appearance. The epidermis of the galls is covered with little
tapering hairs, consisting each of 1-5 cells, to which is due the
velvety down of the drug.
=Chemical Composition=—Chinese or Japanese galls contain about 70
per cent. of a tannic acid, which has been first shown by Stein in
1849 to be identical with that derived from oak galls (see Gallæ
halepenses), the so-called _gallo-tannic_ or common tannic acid.[692]
It is remarkable that this substance, which is by no means widely
distributed, is also present in _Rhus coriaria_, a species indigenous
in the Mediterranean region. Its leaves and shoots are the well-known
dyeing and tanning material _Sumach_.
Stein, however, pointed out at the same time, that in Chinese galls
gallo-tannic acid is accompanied by a small amount, about 4 per cent.,
of a different tannic matter.
=Commerce=—At present the supplies arrive chiefly from Hankow, from
which great trading city the export, in 1872, was no less than 30,949
peculs, equal to 36,844 cwt; 21,611 peculs, value 136,214 taels (one
tael about 6_s._) in 1874. In 1877 all China exported not more than
17,515 peculs. A little is also shipped from Canton and Ningpo.[693]
The quantity imported from China into the United Kingdom in 1872 was
8621 cwts., valued at £20,098. In the China trade returns, the drug
is always miscalled “Nut galls,” or “gallnuts.” Only those called
“Wu-pei-tze” are the galls under examination. There are also oak galls
exported from China resembling those from Western Asia. Japanese galls,
“Kifushi,” are shipped in increasing quantities at Hiogo.[694]
=Uses=—The galls under notice are employed, chiefly in Germany, for the
manufacture of tannic acid, gallic acid, and pyrogallol.
[691] See also Schenk, in Buchner’s _Repertorium für Pharm._ v. (1850)
26-27, or short abstract of that paper in the _Jahresbericht_ of
Wiggers, 1850. 48.
[692] See also Stenhouse, _Proceedings of the Royal Society_, xi.
(1862) 402.
[693] _Returns of Trade at the Treaty Ports of China_, for 1872. 154;
for 1874.
[694] Matsugata, _Le Japon à l’Exposition universelle_ (Paris, 1878)
116. 146.