The period of incubation is from two to ten days. The onset is generally characterized by a rise of temperature from 100 deg.F. to 104 deg.F., chilliness, headache, and pain in the back and limbs. Albuminuria is common. The glands of the neck often become swollen. In mild attacks a slight sore throat is all that is complained of. In the majority of cases the disease attacks the throat and tonsils, and is characterized locally by the appearance of a membrane, which is usually gray or yellowish-white, elastic, and adheres tightly to the surface upon which it lies. At times, however, the membrane is soft and pliable, and is easily separated from the tissue; such cases are frequently diagnosticated as follicular tonsillitis. A bad cold is occasionally the only symptom of the disease. The diagnosis should always be confirmed by bacteriologic examination. In some instances the wind-pipe is primarily attacked, but when the disease affects this part of the throat it is generally a consequence of the extension of the membrane downward from the region of the tonsils. In the former case the diagnosis is somewhat difficult, as cultures taken from the throat may not show the presence of diphtheria bacilli, though material that is coughed up may contain myriads of the germs; in this phase of the disease interference with respiration is the symptom most to be feared. The mucous membrane of the nose, eyes, ears and generative organs, may be affected. Wounds are also liable to become infected with this organism. In rare instances the membrane may extend down into the bronchial tubes and lungs, and has been found on post-mortem examination covering the inside of the stomach. As complications we may have broncho-pneumonia, acute Bright's disease, inflammation of the internal structures of the ears, bleeding from the nose, inflammation of the valves of the heart, and sometimes paralysis of this organ, with death; the last named sequel of diphtheria comes on during convalescence, usually from two to four weeks after the subsidence of local symptoms, and is due to inflammation of the nerves that control the heart. Much less commonly paralytic conditions of the palate, throat, eye muscles and the nerves of taste occur, and under rare conditions, paralysis of the lower extremities. Paralysis of some kind follows in from ten per cent. to fifteen per cent. of the cases, and appears with equal frequency after the mildest as well as following the most severe cases.