In the absence of any knowledge of the infective agent, we are in this disease, as in the case of scarlet fever, left to inference as to the principal seat and mode of action of the infection. The infection IB volatile, and it seems specially virulent in the early stages of the disease. The local symptoms consist mainly in catarrhal inflammation of the mucous membranes of the nasal and respiratory passages, often going on to inflammation of the lungs, and in an eruption in the skin which is also inflammatory. There is more than a simple congestion as in scarlet fever, so that after death infiltration of leucocytes is visible, especially around the sebaceous and sweat glands. There may also be small haemorrhages. Whether the infective agent remains localized in the respiratory tract, and only the toxines are present in the blood, or whether the infection itself reaches the blood, is unknown.