the lungs has not, properly speaking, any circulation Air plants

pl. ( Bot. ) A common name applied there. After entering through the trachea, and pa ing through the bronchial tubes and the intercellular pa ages, it inflates the terminal air-cells, which, being closed at their extremities, arrest its further progre . After a full inspiration, these air-cells are inflated and distended. During the succeeding expirations a part of the air in them, but about one tenth of it only, is expelled. The alternate proce of inspiration and expiration is not therefore the alternate inflation and evacuation of the lungs, but merely one in which they are alternately more or le distended by air. In an adult, the dimensions of the air-cells vary from the 70th to the 200th of an inch. - In Birds , the air-cel is, air-chambers, or air-sacs, are formed by a number of membranes subdividing and intersecting the thoracic-abdominal cavity; and in birds of strong wing and rapid flight, they extend often themselves into the bones. These remarkable cavities are connected with the respiratory system, but their principal use is that of rendering the body specifically lighter. For the air-tubes of Insects and Annelid a , see SPIRAL VESSELS. ( Bot .) The cavities in the leaves or stems, or other parts, containing air. In water-plants they have a very definite form, and are built up of little vesicles of cellular ti ue, with as much regularity as the walls of a house; they, no doubt, enable the plant to float. In plants which do not float, as in the pith of the walnut-tree, their form is le definite; they often appear to be mere lacerations of a ma of cellular substance, and their object is unknown. Air-chambers, n . pl . See AIR-CELLS. Air-cushion. See AIR-BED. Air-drawn, a. Drawn or painted in air. (o.) "This is the air - drawn dagger which led you to Duncan."-Shak. Ai'rdrie, one of the most flourishing inland towns in Scotland, parish of New Monkland, Lan arks hire, 11 miles E. of Glasgow. Ind . Weaving of cotton goods and distillation of spirits. Pop . 15,133. Aire, a small river of England, which rises in the West Riding of Yorkshire. Its source is a sheet of water about a mile in circumference, called Malham Tarn. After flowing 42 miles, it forms a junction with the river Calder. Aire', a city of France, dep. Landes, on the Adour, 80 miles S. S. E. of Bordeaux. It is the ancient Vicus Julii, and has been since the 15th century the seat of a bishopric. Pop . 4,351. Aire', a city of France, dep. Pas de Calais, at the confluence of the Lis and Laquette. Its fortifications are of great importance for the defence of the country between the Lys and the Aa. Рор . (1895) 8,303. Air-embraced, a. Encompa ed by air. to Epiphytes , or plants which grow on frees or other elevated objects, not in the earth, and derive their nutriment from atmospheric moisture. They are to be distinguished from terrestrial plants, or those growing in earth, and from parasites , which derive nourishment directly from other plants on which they grow. The Lichens and Mo es that abound on the trunks or boughs of trees, or on old walls, fences, or rocks, from which they obtain nourishment, are air 2 Fig . 61.-AIR-PLANTS. 1 plants. But the name is generally restricted to flow ering plants of the Orchidaceae (Orchis fam.) and Brome liaceæ (Pine-apple fam.) living in the tropical parts of Aruerica, where a constantiy moist state of the atmos CLASS