_Etiology_.--The accidental swallowing of caustic alkali in solutions of lye or proprietary washing and cleansing powders, is the most frequent cause of cicatricial stenosis. Commercial lye preparations are about 95 per cent sodium hydroxide. The cleansing and washing powders contain from eight to fifty per cent of caustic alkali, usually soda ash, and are sold by grocers everywhere. The labels on their containers not only give no warning of the dangerous nature of the contents nor antidotal advice, but have such directly misleading statements as : "Will not injure the most delicate fabric," "Will not injure the hands," etc. Utensils used to measure or dissolve the powders are afterward used for drinking, without rinsing, and thus the residue of the powder remaining is swallowed in strong solution. At other times solutions of lye are drunk in mistake for water, coffee, or wine. These entirely preventable accidents would be rare if they were as conspicuously labelled "Poison" as is required by law in the case of these and any other poisons, when sold by druggists. The necessity for such labelling is even greater with the lye preparations because they go into the kitchen, whereas the drugs go to the medicine shelf, out of the reach of children. "Household ammonia," "salts of tartar" (potassium carbonate), "washing soda" (sodium carbonate), mercuric chloride, and strong acids are also, though less frequently, the cause of cicatricial esophageal stricture. Tuberculosis, lues, scarlet fever, diphtheria, enteric fever and pyogenic conditions may produce ulceration followed by cicatrices of the esophagus. Spasmodic stenosis with its consequent esophagitis and erosions, and, later, secondary pyogenic infection, may result in serious cicatrices. Peptic ulcer of the lower esophagus may be a cause. The prolonged sojourn of a foreign body is likely to result in cicatricial narrowing. [FIG. 97.--Schematic illustration of a series of eccentric strictures with interstrictural sacculations, in the esophagus of a boy aged four years. The strictures were divulsed seriatim from above downward with the divulsor, the esophageal wall, D, being moved sidewise to the position of the dotted line by means of a small esophagoscope inserted through the upper stricture, A, after divulsion of the latter.] _Location of Cicatricial Esophageal Strictures_.--The strictures are often multiple and their lumina are rarely either central or concentric (Fig. 97). In order of frequency the sites of cicatricial stenosis are: 1. At the crossing of the left bronchus; 2. In the region of the cricopharyngeus; 3. At the hiatal level. Stricture at the cardia has rarely been encountered in the Bronchoscopic Clinic. Stenosis of the pylorus has been noted, but is rare.