_Characters of the false membranes._ These are gray or yellowish white, though they may be reddened in patches or streaks. They vary in consistency from that of glairy mucus to a firm layer as of dense fibrine, and become more adherent as they are of older standing. Sometimes they are partially detached, the free end of the shreds floating in the larynx. The deep or attached surface presents redness in points, in streaks, or as ramifications very visible if the membrane is held up between the eye and the light. They vary in thickness from half to a line. Delafond has found these membranes in the lower animals to be mostly formed of fibrine, with a little albumen, and traces of alkaline and earthy salts. _Treatment._ This must be prompt and energetic. Wet cloths as hot as the hands can bear, wrapped around the throat and neck, and replaced as they cool, will usually arrest the spasm. If this fails ether or chloroform by inhalation or chloral hydrate by injection may be employed with caution. The action of the bowels must be secured by salines (sulphate of soda ½ to 1 ℔) or oil (linseed oil ½ to 1 pint) and injections of warm water. Sulphate of soda should be thereafter given in half ounce doses twice daily, or nitrate or acetate of potass may be substituted. They are advantageously given in linseed decoction and may be combined with laudanum, (½ ounce), belladonna, or other agent to check the spasms. A blister (mustard poultice) should be applied at first either to the throat or breast, the windpipe being left untouched lest tracheotomy should be required. Similar applications to the legs are useful. If suffocation appears imminent _tracheotomy_ should be at once performed (see under Laryngitis). This operation has been depreciated because of the late period at which it has been employed, when the patient was already past all hope, but the resulting wound in the neck is more than counterbalanced by the greater freedom of breathing and the better æration of the blood which tends to obviate the justly dreaded low fever. It often leads to a rapid diminution of the spasms and laryngeal irritation.