GALLÆ HALEPENSES.
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.
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.