Gangrenous coryza is a grave disease of diphtheritic character, which at first seems to be localised in the mucous membrane of the upper respiratory passages, but which exhibits a tendency to affect all the mucous membranes of the system. The term “gangrenous coryza,” adopted in France, has been replaced in other countries, especially in Germany, by such descriptions as “contagious disease of the head,” and “malignant catarrhal fever of the ox.” Old writers describe gangrenous coryza as a disease common in the Jura, the eastern parts of France generally, and in the valley of the Saône. In reality this disease occurs everywhere, both in the centre, west and north of France, as well as in the eastern regions. Serious outbreaks frequently occur in Germany and Italy. =Symptoms.= Gangrenous coryza assumes three different forms, which, however, only represent successive degrees of intensity of the attack. In the peracute form death occurs in three to five days, even when the characteristic signs are not all as yet apparent. In the acute, and by far the most frequent form, the disease lasts from fifteen to twenty days, and also ends in death in by far the greater number of cases. Finally, in the form usually termed chronic, the disease lasts from four to eight weeks, and most frequently ends in recovery. _Acute and peracute forms._—The onset is marked by very striking symptoms, which precede the local symptoms by some hours, or by a day or more. The temperature rises rapidly from the normal to 103° or 105° Fahr. (39·5° to 41° C.), or even higher. Appetite and rumination are entirely suspended; the respiration becomes rapid and difficult, while the heart beats strongly and tumultuously; the muzzle is dry, the mouth hot, and salivation so abundant as to suggest an attack of foot-and-mouth disease. Fæces and urine are only passed at long intervals, and dysuria is present. At first everything seems to indicate the development of an acute infectious disease; but soon afterwards appear local indications affecting the respiratory, ocular, digestive, urinary, nervous and cutaneous systems. The respiratory symptoms are most important, and almost characteristic. Respiration becomes difficult, rough as in acute coryza, but soon assumes a snoring character, and is accompanied by a discharge, containing false membranes, from both nostrils. The serous and muco-purulent discharge becomes rusty or reddish-brown, soon acquires a very fœtid smell, and is found to contain epithelial _débris_ and yellowish-green false membranes. After the least effort to cough or the slightest touch on the membranes themselves—sometimes without any visible cause at all—epistaxis sets in, the blood being mixed with the discharge or simply escaping in the form of reddish strings, like that occasionally seen in glanders. The mucous membrane of the nasal cavities is red, turgid, apt to bleed, and painful to the touch.