4. The gryllus gryllotalpa, or mole cricket, is by far the most curious ; and in its colour and manners differ greatly from the rest. It is of an uncouth and even formidable aspect, measuring more than two inches in length, and is of a broad and slightly flattened shape, of a dusky brown colour, with a ferruginous cast on the under parts, and is readily dis tinguished by the extraordinary structure of its fore-legs, which are excessively strong, and furnished with very broad feet, divided into several sharp claw-shap ed segments, with which it is enabled to burrow under ground in the manner of a mole ; the lower wings, which when ex panded are very large, are, in their usual state, so complicated under the short and small upper wings, or sheaths, that their ends alone appear, reaching, in a sharpened form, along the middle of the back ; the abdomen is terminated by a pair of sharp pointed,lengthened, hairy processes, nearly equalling the length of the antenna in front, and contributing to give this animal an appearance, in some degree, similar to that of a blatta. The mole-cricket emerges from its subter raneous retreats only by night, when it creeps about the surface, and occasion ally employs its wings in flight. It pre pares for its eggs an oval nest, measuring about two inches in its longest diameter; the eggs are about two hundred and or three hundred in number, nearly round, of a deep brownish-yellow colour, and of the size of common shot : on the approach of winter, or any great change of weather, these insects are said to re move the nest, by sinking it deeper, so as to secure it from the power of frost ; and, when the spring commences again, raising it in proportion to the warmth of the sea son, till at length it is brought so near the surface as to receive the full influence of the air and sunshine; but should unfa vourable weather again take place, they again sink the precioukdeposit, and thus preserve it from danger. The young at their first exclusion are about the size of ants, for which, on a cursory view, they might be mistaken; but on a close in spection are easily known by their broad feet, &c. In about the space of a month they are grown to the length of more than a quarter of an inch ; in two months, upwards of three quarters; and in three months, to the length of more than an inch. Of this length they are usually seen
during the close of autumn, after which they retire deep beneath the surface, not appearing again till the ensuing spring. During their groveth they cast their skin three or four times. The mole-cricket lives entirely on vegetables, devouring the young roots of grasses, corn, and va riou,s esculent plants, and commits great devastation in gardens. It inhabits Europe and America.
GUA tAC UM, in botany, a genus of the Decandria Monogynia class and order. Natural order of Gruinales. Rutaceie, Jussieu. Essential character : calyx five cleft, unequal ; petals,live, inserted into the receptacle ; capsule angular, five celled. There are four species. From the G. officinale is obtained a resin, which exudes spontaneously, and is also driven out artificially by means of heat. This substance has been long known and cele brated as a medicine in various cases ; and in the Transactions of the Royal Society for the year 1806, we have a very com plete analysis of it : by distillation 100 parts yielded, Acidulous water - - - 5.5 Thick brown oil - - 24.5 Thin empyreumatic oil - 29.0 Charcoal 30.5 Gases consisting of carbo nic acid and carbureted 10.5 hydrogen - - — 100.0 Hence it is inferred, that guaiacum agrees in many respects with the resins, but it differs from them, 1. in the quanti ty of charcoal it leaves when distilled in close vessels ; 2. in the action that nitric acid has upon it ; and, 3. in the changes of colour that it undergoes When its solu tions are treated with nitric and oxymu riated acids. Its properties may be thus enumerated it is a solid substance re sembling a resin ; its colour varies, but is generally greenish ; it is readily dis solved in alcohol ; alkaline solutions dis solve it with ease : most of the acids act upon it with considerable energy ; if di gested in water, a portion is dissolved, the water acquiring a greemsh-brown co lour : the liquid, being evaporated, leaves a brown substance, which possesses the properties of an extract, being soluble in hot water and alcohol, but scarcely at all in sulphuric ether, and forming precipi tates with the muriates of alumina, tin, and silver.