Where highly irritating decomposing fluids are present in the bronchi, they produce acute inflammation of a suppurative character. This occurs chiefly under three conditions. In the first place local obstruction of bronchi causes the secretion to stagnate and accumulate, and putrid decomposition is liable to occur. This is the mildest form. In the second place foreign bodies lodging in the bronchi give rise to abundant secretion of fluid which decomposes. This is more fully considered at p. 742. Lastly, gangrene of the lung leads to it, by producing putrid juices which pass into the bronchi. In the last two cases the whole bronchi of one lung are liable to be affected, and there may even be an overflow into the other lung. There is also liable to be an extension to the parenchyma of the lung, the putrid juices being insufflated.