08 



CUPUL1FER.E. 



taken not to injure the inner cortical layer, otherwise 

 iio new bark would be produced. After being taken 

 olF, the bark is flattened by exposing its convex sur- 

 face to heat and pressure. It is also charred on both 

 sides, so as to close the transverse pores before being 

 sold. The carbonised surfaces are seen in bungs and 

 taps, but not in ordinary corks which are cut length- 

 wise. The bark gathered in France has been esti- 

 mated as sufficient to form 1 19,000,000 or 120,000,000 

 of corks eighteen lines long. 



Cork was used by the Greeks for sandals, and is 

 occasionally employed now-a-days for lining the soles 

 of shoes. It is also employed to form surgical instru- 

 ments and apparatus, and is essential to the cabinet 

 of the entomologist. 



The charcoal got from it, when mixed with lard, 

 has been recommended in piles. It contains a pecu- 

 liar principle called Subcrin, and an acid called Suberic 

 acid. 



Quercus tinctoria is an American tree which attains 

 the height of eighty or ninety feet with a diameter 

 of four or five feet." It supplies useful timber, and its 

 bark is used for tanning leather. The cellular part 

 of the bark furnishes quercitron, a substance used for 

 dyeing wool and silk of a yellow colour. It is said 

 to be superior to woad. The decoction of quercitron 

 has a brownish yellow colour, which is rendered 

 deeper by alkalies. 



Quercus cocci/era, the kermes oak, grows plentifully 

 in Spain, Provence, Languedoc, and along the coast 

 of the Mediterranean. It is a tree of small growth, 

 being in general not more than twelve feet high. Its 

 acorns are smaller than those of the 'common oak. 

 From this tree is gathered the vegetable kermes, an 

 insect with which the ancients used to dye their gar- 

 ments of a beautiful pink colour. Since the discovery 

 of America, the coccus cacti, or cochineal insect, has 

 supplied the place of the kermes. 



Kermes is met with in commerce in the form of 

 little red globular grains torn on the side where the 

 animal adhered to the leaves or young branches of 

 the oak. According to analysis it consists of yellow 

 fatty matter, red colouring matter analogous to car- 

 mine ; coccine, a peculiar animal matter, and various 

 phosphates and muriates. The colour obtained from 

 the kermes is said to be more fixed than that got from 

 the Mexican insect. 



Quercus esculus, cut-leaved Italian oak, is the small 

 oak or phagus of the Greeks, and the Esculiis of Pliny. 

 It is a native of Spain and Italy, and was used by 

 the Romans to form their civic crowns. Its acorns 

 are sweet, and are frequently eaten by the poor in 

 the South of France, who, in times of scarcity, grind 

 them and make bread with the flour. 



Quercus rubra, red oak, is a native of Virginia and 

 other parts of North America. It extends far north, 

 and grows to the height of eighty feet. It yields 

 large acorns, which are eaten by wild animals, as well as 

 by horses, cows and hogs. Its bark is employed for 

 tanning, but its wood is not much used in building. 



Quercus alba. White oak, so called on account of 

 the whiteness of its bark ; is a native of North Ame- 

 rica, where it reaches the height of seventy or eighty 

 feet, with a diameter of six or seven feet. Its wood 

 is considered in America preferable to any other sort 

 for building, on account of its strength and durability. 

 The wooden bridge which joins Cambridge and Bos- 

 ton, and which is nearly 3000 feet long, is supported 

 by posts of white oak from fourteen to fifty feet long. 



Its bark contains a considerable quantity of tannin, 

 and an infusion of it has been known to cure ague. 

 Its acorns are large, oval, and sweet. 



Quercus virens. Live oak, found in Carolina and 

 Virginia ; yields small acorns, which are eaten by 

 the Indians, and are used by them to furnish a sort of 

 oil. The acorns of Quercus ilex, evergreen oak, are 

 mild and nutritive, and serve for food. The acorns 

 of Quercus cegilops, a native of Spain and the Levant, 

 where it is called Velonia, are imported as a dye-stuft'. 



Many other species of oak might be noticed, such 

 as black oak, scarlet oak, willow oak, chestnut oak, 

 laurel oak, dwarf oak, water oak, &c., most of which 

 are cultivated either on account of their wood or bark ; 

 but it appears unnecessary to dwell longer on the 

 subject, inasmuch as the properties of the oak tribe 

 have been already sufficiently illustrated by the ex- 

 amples which have been adduced. Before, however, 

 proceeding to treat of another genus, we shall make 

 a few remarks on a disease to which the oak is sub- 

 ject, in consequence of the attacks of insects. 



The leaves, flowers, and fruit of almost all vegeta- 

 bles are liable to be attacked by the insect tribe ; 



The flowery leaf 



Wants not its soft inhabitant. Secure 

 Within its winding citadel the stove 

 Holds multitudes. But chief the forest boughs 

 That dance unnumher'd to the playful breeze, 

 The downy orchard and the melting pulp 

 Of mellow fruit, the nameless nations feed 

 Of evanescent insects. 



In some cases their attack is followed by the 

 production of a peculiar substance, which is turned 

 to useful account in a medical or economical point of 

 view, and of this we have an excellent, illustration in 

 the genus now under consideration. Upon the leaves 

 of all the species of oak there are tound globular 

 bodies, to which the name of galls, or gall-nuts, has 

 been given. They are produced by various small four- 

 winged insects, denominated Cynips quercusfolu, or 

 Diplolepis gallce tinctorice, c. The adult female insect 

 is furnished with a long slender spiral sting, with 

 which it punctures the stalk of the oak-leaf, and at 

 the same time deposits a minute egg, and probably 

 some irritating fluid. In consequence of the irritation, 

 which is produced by this wound, the sap is deter- 

 mined to the part, and the extravasated juice flowing 

 around the egg soon forms a soft excrescence, which 

 serves both for the shelter and food of the young 

 insect. The tumour increases very rapidly, until a 

 perfect gall is formed. The larva afterwards issues 

 from the egg, assumes the pupa state, and then 

 escapes as the perfect fly, by perforating the walls of 

 the chamber in which it is inclosed. 



The best galls are those which are gathered before 

 the insect has escaped, and are denominated black, 

 blue, or green galls, on account of their colours. 

 There is of course no perforation in them, and on 

 opening them we find perfect specimens of the fly. 

 Those galls, on the contrary, which are collected 

 after the fly has escaped, are called white galls, and 

 are not so much esteemed, containing less astringent 

 principle than the entire galls in the proportion of 

 two to three. 



The oak on which the finest galls are found is 

 described by Olivier, in his Travels in the Ottoman 

 Empire, as the Quercus infectoria, a small tree grow- 

 ing in Asia Minor. The galls are collected by the 

 poorer inhabitants, and are exported from Smyrna, 

 Aleppo, and vari as parts of the Levant. 



