less fatal to the vegetable substance to which they are attached. According to Virey, an irritation is produced by the introduction of these insects, that resembles a tumour and inflammation in an animal body. The cellular tissue swells; the parts, which were naturally long, become round; and the flow of liquid matter produces a change of organization, from which results a complete change in the external form of the organ. In this way is the gall produced. The oak-apple is an excrescence of the same nature, though effected by a different species of insect. There are various insects possessing the instinct thus to deposit their eggs, that are furnished with an apparatus of the most curious construction, necessary for puncturing the branch, as is done by the parent; and for piercing a way out of the gall, as is done by the insect produced, after it has passed its larva state. Each species of insect chooses not only the particular vegetable, but the part of that vegetable which is best adapted for the reception of its larvæ; and in this way the same plant, for instance the oak, sometimes receives the nests of twenty different species of insects. A gall sometimes contains a single larva, sometimes many, and it is thus either called simple or compound. A late agreeable writer on Natural History has given us some sensible observations on the subject of galls, and the instincts of the little creatures that produce them :

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The insect that wounds the leaf of the oak, and occasions the formation of the gall-nut, and those which are likewise the cause of the apple rising on the sprays of the same tree, and those flower-like leaves on the buds, have performed very different operations, either by the instrument that inflicted the wound, or by the injection of some fluid to influence the action of the parts. That extraordinary hairy excrescence on the wild rose, likewise the result

of the wounds of an insect (cynips rosa), resembles no other nidus required for such creatures that we know off; and these red spines on the leaf of the maple are different again from others. It is useless to inquire into causes of which we probably can obtain no certain results; but, judging by the effects produced by different agents, we must conclude, that, as particular birds require and fabricate from age to age very different receptacles for their young, and make choice of dissimilar materials, though each species has the same instruments to effect it, where, generally speaking, no sufficient reasons for such variety of forms and texture is obvious; so is it fitting that insects should be furnished with a variety of powers and means to accomplish their requirements, having wants more urgent, their nests being at times to be so constructed as to resist the influence of seasons, to contain the young for much longer periods, even occasionally to furnish a supply of food, or be a storehouse to afford it when wanted by the infant brood*."

Reaumur, the distinguished naturalist, in his Memoirs on Insects, has a most minute and interesting account of the admirable mechanism by which the genus Cynips (the insect which produces the gallnut) conducts its remarkable operations. It is provided with a needle in a sheath, which has most surprising powers of extension, derived from the peculiar construction of the whole body of the insect, so much so that the needle can be extended to double the length of the animal itself; and thus, as we have seen, it forms a nest for its offspring, while the young, in the same manner, pierce their way out of the vegetable shell which has been their protection. In Spain, in the southern provinces of France, and along the Mediterranean coasts of Africa, there is * Journal of a Naturalist, page 109.

found in great plenty a small species of oak, called the Kermes (Quercus coccifera), which is remarkable for nourishing large quantities of a small insect (Coccus ilicis), which, being gathered, forms an article of commerce called kermes. The declivities of the Sierra Morena are covered with the kermes oak; and many of the inhabitants of the province of Murcia have no other mode of living than gathering the kermes. Latreille has united this insect to the cochineal family, which it resembles, not only in its form, but in producing a scarlet dye. Till the discovery of the cochineal insect upon certain species of the Cactus in South America, the kermes was the only substance used in dyeing scarlet, from the period of the disuse and loss of the Murer and Buccinum, the shell-fish that produced the Tyrian purple of the Romans. The people of Barbary employ the kermes for dyeing the scarlet caps used by the natives in the Levant, and they prefer that of Spain to their own produce. In England, and in other countries where manufactures are extensively carried on, the cochineal has almost entirely superseded the use of the insect scarlet dye of Europe.

Though the TEAK TREE (Tectona grandis) be a tree of quite a different family from the oak, and a native of India, it is used in ship-building like the oak, and has some resemblance to it in its timber. It is a tree of uncommon size, with leaves twenty inches long, and sixteen broad, and bears a hard nut. The country ships in India, as well as many very fine ones that trade between India and this country, are built of it. A specimen was introduced into the Royal Gardens at Kew, about sixty years ago; but from the warmth of the climate of which it is a native, it can never become a forest-tree in this country.

Besides its value as timber, the teak has great beauty as a tree. It is found more than two hundred feet high, and the stem, the branches, and the leaves are all very imposing. On the banks of the river Irrawaddy, in the Birman empire, the teak forests are unrivalled; and they rise so far over the jungle or brushwood, by which tropical forests are usually rendered impenetrable, that they seem almost as if one forest were raised on gigantic poles over the top of another. The teak has not the broad strength of the oak, the cedar, and some other trees; but there is a grace in its form which they do not possess.

CHAPTER II.

THE PINE.

ALTHOUGH, in all or most of its species, not next to the oak in the strength or the durability of its timber, the Pine, perhaps, claims the second place among valuable trees. It is very abundant, its growth is comparatively rapid, and its wood is straight, elastic, and easily worked. Accordingly, as oak is the chief timber in building ships for the sea, pine is the principal one in the construction of houses upon land. It is "the Builder's timber:" and as, when the carpenter wants a post or a beam of peculiar strength and durability, he has recourse to the oak; so when the shipwright wishes to have a piece of timber that shall combine lightness with great length, as for a spar or mast, he makes use of the pine.

The distinct species of pines enumerated by the botanists are about twenty-one. None of these bear flat leaves, but a sort of spines, which, however, are true leaves. They are mostly, though not all, evergreens; but the appearance of the tree, as well as the quality of the timber, varies with the species, and also with the situation in which it grows. Generally speaking, the timber is the more hard and durable the colder the situation is, and the slower the tree grows; and in peculiar positions it is not unusual to find the northern half of a common pine hard and red, while the southern half, though considerably thicker from the pith to the bark, is white, soft, and spongy.

No account can be given of the first use of the different species of pines by the natives of the coun