_Gallæ Turcicæ_; _Galls_, _Nutgalls_,
_Oak Galls_, _Aleppo_ or _Turkey Galls_;
F. _Noix de Galle_, _Galle d’Alep_;
G. _Levantische oder Aleppische Gallen_,
_Galläpfel_.
=Botanical Origin=—_Quercus lusitanica_ Webb, var. _infectoria_ (_Q.
infectoria_ Oliv.),[2227] a shrub or rarely a tree, found in Greece,
Asia Minor, Cyprus and Syria. It is probable that other varieties of
this oak, as well as allied species, contribute to furnish the Aleppo
galls of commerce.
=History=—Oak galls are named by Theophrastus, and were well known to
other ancient writers. Alexander Trallianus prescribed them as a remedy
in diarrhœa.[2228]
The earliest accurate descriptions and figures of the oak and the
insect producing the galls are due to Olivier.[2229] Pliny[2230]
mentions the interesting fact that paper saturated with an infusion
of galls may be used as a test for discovering sulphate of iron, when
added as an adulteration to the more costly verdigris: this, according
to Kopp, is the earliest instance of the scientific application of a
chemical reaction.[2231] For tanning and dyeing, galls have been used
from the earliest times, during the middle ages however they were not
precisely an article of great importance, being then, no doubt, for a
large part replaced by sumach.
Nutgalls have long been an object of commerce between Western Asia and
China. Barbosa in his _Description of the East Indies_[2232] written
in 1514 calls them _Magican_,[2233] and says they are brought from the
Levant to Cambay by way of Mekka, and that they are worth a great deal
in China and Java. From the statements of Porter Smith[2234] we learn
that they are still prized by the Chinese.
[2227] De Candolle, _Prodromus_, xvi. sect. 2. fasc. i. 17.
[2228] Puschmann’s edition, quoted in the Appendix, i. 237.
[2229] _Voyage dans l’Empire Othoman_, ii. (1801), pl. 14-15.
[2230] Lib. 34. c. 26.
[2231] _Geschichte der Chemie_, ii. (1844) 51.
[2232] Published by the Hakluyt Society, Lond. 1866. 191.
[2233] Nearly the same name is still used in the Tamil, Telugu,
Malayalim and Canarese languages.
[2234] _Mat. Med. and Nat. Hist. of China_, 1871. 100.
=Formation=—Many plants are punctured by insects for the sake of
depositing their eggs, which operation gives rise to those excrescences
which bear the general name of _gall_.[2235]
Oaks are specially liable to be visited for this purpose by insects
of the order _Hymenoptera_ and the genus _Cynips_, one species of
which, _Cynips Gallæ tinctoriæ_ Olivier (_Diplolepis Gallæ tinctoriæ_
Latreille), occasions the galls under notice.
The female of this little creature is furnished with a delicate borer
or ovipositor, which she is able to protrude from the extremity of the
abdomen; by means of it she pierces the tender shoot of the oak, and
deposits therein one or more eggs. This minute operation occasions an
abnormal affluence to the spot of the juices of the plant, the result
of which is the growth of an excrescence often of great magnitude, in
the centre of which (but not as it appears until the gall has become
full-grown) the larva is hatched and undergoes its transformations.
When the larva has assumed its final development and become a winged
insect, which requires a period of five to six months, the latter
bores itself a cylindrical passage from the centre of the gall to its
surface, and escapes.
In the best kind of gall found in commerce, this stage has not yet
arrived, the gall having been gathered while the insect is still in
the larval state. In splitting a number of galls, it is not difficult
to find specimens in all stages, from those containing the scarcely
distinguishable remains of the minute larva, to those which show the
perfect insect to have perished when in the very act of escaping from
its prison.
=Description=—Aleppo galls[2236] are spherical, and have a diameter of
⁴/₁₀ to ⁸/₁₀ of an inch. They have a smooth and rather shining surface,
marked in the upper half of the gall by small pointed knobs and ridges,
arranged very irregularly and wide apart; the lower half is more
frequently smooth. The aperture by which the insect escapes is always
near the middle. When not perforated, the galls are of a dark olive
green, and comparatively heavy; but after the fly has bored its way
out, they become of a yellowish-brown hue, and lighter in weight. Hence
the distinction in commerce of _Blue_ or _Green Galls_, and _White
Galls_.
[2235] French writers, as Moquin-Tandon, distinguish the thick-walled
galls of _Cynips_ from the thin, capsular galls formed by _Aphis_,
terming the former _galles_ and the latter _coques_ (shells).
[2236] There are many other varieties of oak gall, for descriptions
of some of which, see Guibourt, _Hist. des Drogues_, ii. (1869)
292; and for information on the various gall-insects of the family
_Cynipsidæ_ and the excrescences they produce, consult a paper by Abl
in Wittstein’s _Vierteljahresschrift für prakt_. _Pharm._ vi. (1857)
343-361.
Aleppo galls are hard and brittle, splitting under the hammer;
they have an acidulous, very astringent taste followed by a slight
sweetness, but have no marked odour. Their fractured surface is
sometimes close-grained, with a waxy or resinous lustre; sometimes
(especially towards the kernel-like centre) loosely granular, or
sometimes again it exhibits a crystalline-looking radiated structure or
is full of clefts. The colour of the interior varies from pale brown
to a deep greenish yellow. The central cavity, sometimes nearly ¼ of
an inch in diameter, which served as a dwelling for the insect, is
lined with a thin hard shell. If the insect has perished while still
very young, the central cavity and the aperture contain a mass of loose
starchy cellular tissue, or its pulverulent remains: if the insect has
not been developed at all, the centre of the gall is entirely composed
of this tissue.
=Microscopic Structure=—The cellular tissue of the gall is formed in
the middle layer of large spherical cells with rather thick porous
walls, becoming considerably smaller towards the circumference. The
outermost rows are built up of cells having but a very small lumen
and comparatively thick walls, so that they form a sort of rind. Here
and there throughout the entire tissue, there occur isolated bundles
of vessels which pass through the stalk into the gall. Towards the
kernel, the parenchyme gradually passes into radially-extended,
wider, thin-walled cells, the walls of which are marked with spiral
striæ. The hard shell of the chamber[2237] is composed of larger,
radially-extended, thick-walled cells, with beautifully stratified
porous walls. On the inner side of this shell there are found, after
the escape of the insect, the remains of the starchy tissue already
mentioned, which originally filled the chamber and had been consumed by
the insect as nourishment.
[2237] _Couche protectrice_ of Lacaze-Duthiers—_Recherches pour servir
à l’histoire des galles_.—_Ann. des Sciences Nat._, Bot. xix. (1853)
273-354.
The parenchyme-cells outside the shell contain chlorophyll and tannin;
the latter is in transparent, colourless, sharp-edged masses, insoluble
in benzol, but dissolving slowly in water, quickly in alcohol. Thin
slices soaked in glycerin appear after some time covered with beautiful
crystals of gallic acid. The thick-walled cells (stone-cells) and the
neighbouring striated cells, are rich in octahedra of calcium oxalate.
The tissue of the gall situated within the shell of thick-walled cells
contains starch in large, compressed, mostly spherical granules; also
isolated masses of brown resin. Besides these, there appears to be in
this part of the tissue an albuminoid compound.
=Chemical Composition=—The rough taste of galls is due to their chief
constituent, _Tannic_ or _Gallo-tannic Acid_, C₁₄H₁₀O₉, or
C₆H₂(OH)₂COOH}
}O
C₆H₂(OH)₂CO}
the type of a numerous family of substances to which vegetables owe
their astringent properties. Tannic matter was long supposed to be
of one kind, namely that found in the oak gall, but the researches
of later years have proved the tannin of different plants to possess
distinctive characters: hence the term _gallo-tannic_ acid to
distinguish that of galls, from which it is principally derived. It
was however shown by Stenhouse as far back as the year 1843, again in
1861, as well as by still more recent unpublished experiments, that the
tannic acid found in Sicilian sumach, the leaves of _Rhus Coriaria_
L., is identical with that of oak galls. Löwe in 1873 came to the same
conclusion. The best oak galls yield of this acid, from 60 to 70 per
cent.
_Gallic Acid_ is also contained in galls ready-formed to the extent of
about 3 per cent. Free sugar, resin, protein-substances, have also been
found. Neither gum nor dextrin is present.
=Commerce=—The introduction into dyeing of new chemical substances,
and the increased employment of sumach and myrobalans, have caused the
trade in nutgalls to decline considerably during the last few years.
The province of Aleppo which used to export annually 10,000 to 12,000
quintals, exported in 1871 only 3000 quintals.[2238] A staple market
for the galls which are collected in the mountains of Kurdistan is
Diarbekir, whence they are sent to Trebizond for shipment. Galls are
also shipped in some quantity at Bussorah, Bagdad, Bushire, and Smyrna.
There were imported into the United Kingdom from ports of Turkey and
Persia during 1872, 6349 cwt. of galls, valued at £18,581.
=Uses=—Oak galls in their crude state are seldom used in medicine
unless it be externally; but the tannic and gallic acids extracted from
them are often administered.
Other kinds of Gall.
_Chinese or Japanese Galls_—The only kind of galls, besides those of
the oak, which are of commercial importance. They are described at page
167.
_Pistacia Galls_—The genus _Pistacia_, which belongs to the same order
as _Rhus_, is very liable to the attacks of _Aphis_, which produce
upon its leaves and branches excrescences of exactly the same nature
as Chinese galls. In the south of Europe, horn-like follicles, often
several inches long,[2239] are frequently met with on the branches
of _Pistacia Terebinthus_ (page 165). These _Gallæ vel Folliculi
Pistacinæ_, in Italian _Carobbe di Giudea_, were formerly used in
medicine and in dyeing.[2240] They were noticed in 1555 by Belon, but
already well known as early as the time of Theophrastus.
Another much smaller gall of different shape is formed (by the same
insect?) on the ribs of the leaves of _Pistacia Terebinthus_; _P.
Lentiscus_ (page 161) affords also a similar small excrescence.
Again, another growth of the same character constitutes the small
and very astringent galls known in the Indian bazaars by the names
of _Bazghanj_ and _Gule-pistah_, the latter signifying _flower of
pistachio_; they have been termed in Europe _Bokhara Galls_. They were
imported by sea into Bombay in the year 1872-73, to the extent of 184
cwt., chiefly from Sind;[2241] and are also carried into North-western
India by way of Peshawar and by the Bolan Pass. Occasionally a package
finds its way into a London drug sale.
_Tamarisk Galls_—These are roundish knotty excrescences of the size
of a pea up to ½ an inch in diameter, found in North-western India on
the branches of _Tamarix orientalis_ L., a large, quick-growing tree,
common on saline soils. The galls are used in India in the place of
oak galls, and are mentioned as “non-officinal” in the _Pharmacopœia
of India_, 1867. We are not aware that they have been the subject of
any particular chemical research; their microscopic structure has been
investigated by Vogl.[2242]
[2238] Consul Skene—_Reports of H. M. Consuls_, No. 1. 1872. 270.
[2239] For a figure, see _Pharm. Journ._ iii. (1844) 387. For the
structure see Marchand, in the paper quoted at page 166, note 4, plate
iii.
[2240] Analysis by Martius may be found in Liebig’s _Ann. d. Pharm._
xxi. (1837) 179.
[2241] From the returns quoted at page 333, note 3.
[2242] _Zeitschrift des Oesterreichischen Apothekervereines_, 1877. 14.