When a lung in this state has been inflated and dried it presents on the diseased parts the union of several air sacs into one by the rupture of their intervening walls so that a pea may be lodged in the cavity; it further shows wide and prolonged canals on the surface and in the intervals between the lobules—the dilated areolæ of the connective tissue. These abnormal conditions like the vesicular emphysema are chiefly met with in the anterior lobes of the lungs along their free borders and on their inner surface near the entrance of the bronchi. One or both of these two forms of emphysema may be considered as essential conditions in all forms of broken wind. It does not follow that this is the primary disease; we have already seen that the cause of the malady is usually to be sought on the side of the digestive organs, and that impaired innervation, on the part of the vagus nerve or of the ganglia in the brain presiding over it, leads to these functional and structural changes in the lungs. If these changes are results and not causes, their extent will not necessarily bear a constant proportion to the intensity of the disease, though in reality they are generally found to do so. From a series of injections of lungs from broken winded horses M. Demoussy arrived at the conclusion that the essential lesion of broken wind was an aneurismal dilatation of the capillary vessels of the lung. This is like the condition of the mucosa found in asthma in man and is explainable in both cases by the impaired innervation, as dilatation of these minute vessels is a natural consequence of the loss of vaso-motor nervous power, and contact with air saturated with carbonic acid. Dilatation of the smaller bronchial tubes is frequently present and especially characterises such cases as supervene on chronic bronchitis. These dilated tubes contain a plastic, whitish, inodorous mucus. Another frequent concomitant of the emphysematous lung is a dilatation of the right cavities of the heart, especially the auricle, and an attenuation of their walls. The same condition is noticed in pulmonary emphysema in man and like this is probably due to the slow and imperfect circulation in the diseased lung. Collating these structural changes with the different causes of the disease we find that they harmonize with the theory of impaired function on the part of the vagus nerve or its presiding ganglia, whether this functional disturbance has its origin in disorder of the digestive organs, as in the great majority of cases, in severe muscular efforts, or in chronic bronchitis.