_Lesions in the Protracted and Chronic Forms._ The lesions of the skin are usually less extensive than in the acute type, and may be almost entirely absent. The lymph glands are enlarged and congested, though the discoloration may be largely confined to the cortical layer. The spleen is as a rule normal in size. The liver is firm, but it may show softening of the secreting acini and encrease of the fibrous framework. Petechiæ or circumscribed hæmorrhages may or may not be present on or under the serosæ or in the tissues. The characteristic lesions belong to the gastric-intestinal organs. Congestions and ulcers may be found on the gastric mucosa, on that of the small intestine, and rectum, but they are above all common on the ileocæcal valve, cæcum and first half of the colon. In the earlier stages of these lesions the mucosa and submucosa are the seat of a congestion and exudation, but later the round button-like ulcer usually stands out prominently with its necrotic centre dirty white, brown or black, and composed of superposed layers, the whole resting on a congested and thickened submucosa. This contains small round and giant cells and may show considerable encrease in connective tissue. The ulcers may be seated on the agminated or solitary glands but do not show the same predilection for these parts which is seen in typhoid fever. _Incubation._ This varies according to the dose and susceptibility from two or three to as many as thirty days. With the short incubation the disease tends to assume its most acute and deadly type, while the prolonged incubation bespeaks a milder form. During ordinary outbreaks from six to fourteen days represent the average interval between exposure and the onset of active symptoms. During the extreme heats of summer and the excessive cold of midwinter in our northern states incubation tends to be shortened. _Symptoms in Fulminant Type._ In violent outbreaks some pigs are found dead without observed preliminary symptoms, and have been set down as fulminant examples of the disease. When these occur during very hot weather, in open yards or fields, there is reason to believe that insolation, acting on a system rendered specially susceptible by the toxic fever, has much to do with the early death. Though seldom observed during life, it has been said that such cases, show extreme dulness, prostration, stupor, weakness, unsteady gait, thirst, hyperthermia, persistent recumbency, and at times red blotching of the skin and even convulsions.