=Symptoms.=--Whooping cough begins like an ordinary cold in the head, with cough, worse at night, which persists. The coughing fits increase and the child gets red in the face, has difficulty in getting its breath during them, and sometimes vomits when the attack is over. After a variable period, from a few days to two weeks from the beginning of the cough, the peculiar feature of the disease appears. The child gives fifteen or twenty short coughs without drawing breath, the face swells and grows blue, the eyeballs protrude, the veins stand out, and the patient appears to be suffocating, when at last he draws in a long breath with a crowing or whooping sound, which gives rise to the name of the disease. Several such fits of coughing may follow one another and are often succeeded by vomiting and the expulsion of a large amount of phlegm or mucus, which is sometimes streaked with blood. In mild cases there may be six to twelve attacks in twenty-four hours; in severe cases from forty to eighty. The attacks last from a few seconds to one or two minutes. Occasionally the whoop comes before the coughing fit, and sometimes there may be no whooping at all, only fits of coughing with vomiting. Between the attacks, puffiness of the face and eyes and blueness of the tongue persist. The coughing fits and whooping last usually from three to six weeks, but the duration of the disease is very variable. Occasionally it lasts many months, especially when it occurs in winter. The contagiousness of whooping cough continues about two months, or ceases before that time with the cessation of the cough. Oftentimes there may be occasional whooping for months; or, after ceasing altogether for some days, it may begin again. In neither of these conditions is the disease considered still contagious after two months. When an attack of whooping is coming on, the child often seems to have some warning, as he seems terrified and suddenly sits up in bed, or, if playing, grasps hold of something, or runs to his mother or nurse. Coughing fits are favored by emotion or excitement, by crying, singing, eating, drinking, sudden change of temperature, and by bad air.