inspired air, it becomes evident that any increase in the force of the current will aggravate it and a decrease will lessen the extent of the closing and alleviate the distress of breathing. This fact furnishes a means of palliating the symptoms. (See treatment.) It explains moreover why roaring should not be heard in quiet breathing and why it should increase in force and in pitch as the respiration becomes more and more hurried. It further accounts for the noise being heard only during the act of inspiration, the outward rush of the air in the expiratory act being of itself sufficient to carry this valvular cartilage out of the passage and secure a free and unimpeded current. The paralysis and wasting of the left recurrent nerve and muscles are in their turn due to very varied morbid states. It may commence in the larynx from distortion of its cartilages and inflammation of the mucosa, in which case the wasting of the nerve is probably a result of its prolonged inactivity. This mode of origin is strongly insisted on by Percivall, and no doubt occasionally arises. Under this explanation, however, it is difficult satisfactorily to account for its almost invariable occurrence on the left side. The mere fact that the horse is habitually approached on this side and more commonly turned toward it is a most insufficient reason. Even if admitted it utterly fails to explain the immunity of the muscles supplied by the superior laryngeal nerve. The fact that a horse has usually a hard and soft side of the mouth and carries the head slightly to the latter is no better explanation, as the tender side is not always the left. More commonly the disease arises at some other point near the origin or in the course of the nerve, and the changes in the larynx follow as the consequence of deficiency or entire absence of motor innervation. Many cases can be cited in which such an origin was unquestionable, and on the hypothesis that this is the true and constant history of the development of the malady, its regular occurrence in the left side, and the absence of all signs of wasting in the muscles supplied by the superior laryngeal nerve are alike perfectly explainable.