_Suppuration._ _Abscess._ The great variety of the causes and forms of suppuration would forbid any extended notice of its treatment in this place. It seems preferable to refer the reader to the subject of pyæmid and the various surgical and medical diseases in which suppuration takes place. DISEASES OF THE RESPIRATORY ORGANS. Importance of diseases of the respiratory organs—in horses and dogs. Proclivity through over-exertion, through extent and delicacy of the mucosa, through changes of temperature, through weather, through air pollution, through kind of diet, through change of latitude, through nervous sympathy, through debilitation of the lung tissue, through suppression of perspiration, through a high dew point, through bacteria and other germs, through youth and change of habits. These are among the most frequent and grave of all affections of the domestic animals. They are especially important however in the case of animals that depend on the soundness of their wind. In horses and dogs accordingly any permanent injury to the organs of respiration will seriously impair the value, not only because of the diminished usefulness of the affected animal, but also because of the probable deterioration of their progeny. The rapid paces demanded of these animals and the strain to which the respiratory organs are subject are potent causes of respiratory disorder. In all animals, however, the extent of the respiratory surface and its extreme delicacy and tenuity especially predispose it to disease. Hales estimates that the mucous membrane covering all the air sacs and air cells is, in the calf, no less than 250 square feet. As the chest of the horse is at least double that of the calf, and as it contains much less connective tissue, and is made up of minute air cells from ¹⁄₇₀–¹⁄₂₀₀ inch in diameter and separated from each other by walls so attenuated that the contained capillary bloodvessels are equally exposed to the air on both sides, in two adjacent air cells, the estimate for the average horse must be considerably above 500 square feet. This membrane, incomparably the most delicate and susceptible in the animal economy, is constantly in contact with the air in all its variable conditions, and is necessarily affected by these variations.