In 1922 A. Fleming brought out some interesting facts in regard to the lytic substance present in the tissues and secretions of the body, which is capable of rapidly dissolving certain bacteria.He called it “Lysozym. ” A. Fleming and other investigators found Lysozym present in the tissues and secretions of the human body, animals and vegetables. But no one has studied the Lysozym in the mucous membrane of the human nose, tissue of the throat and pus of the ear.I first studied the lysozym which is present in the mucous membrane of the human nasal cavity (the normal or the hypertrophied mucous membrane of the iuferior, middle turbinated body) and mucous membrane of the human accessory nasal cavity (the normal or the affected membran). Further, I investigated it in the hypertrophied raucial tonsils, in the pharyngeal tonsils, in the impacted cerumen and in pus from peritonsillitis and from Schwartze's operation of mastoiditis. I extracted the membrane of these tissues and impacted cerumen with physiological salt solution. The organism used in this work is Bacillus Z, which was isolated by Bail in his laboratory.The summary of my experiments is as follows:1. I have first investigated the Lysozym in the mucous membrane of the human nasal cavity, accessory nasal cavity, pharyngeal tonsil and inpacted cerumen.2. The Lysozym in one normal mucous membrane of the nasal cavity partially dissolved the suspension of Baccillus Z, in 1: 7000 dilution. The Lysozym in the hypertrophied mucous membrane of the nasal cavity in 8 cases partially dissolved the Bacillus Z, in dilutions ranging from 1: 20000 to 1: 80000. The Lysozym in one normal membrane of the maxillary cavity partially dissolved the Bacillus Z, in 1: 7000 dilution, and in diseased maxillary cavity tissue in 9 cases partially dissolved the Bacillus Z, ranging between 1: 30000 and 1: 80000 dilution.In these few cases, the Lysozym in the normal tissues shows a weaker action than in the diseased tissues.3. The bacteriolytic action of the Lysozym in the membrane of the frontal cavity against the Bacillus Z, took place at the 1: 10000 dilution in one case.4. The bacteriolytic action of the Lysozym in the hypertrophied faucial tonsils in 6 cases occurred in dilution between 1: 7000 to 1: 50000.5. The bateriotytic action of the Lysozym contained in the hypertrophied pharyngeal tonsils took place in 1: 20000 to 1: 60000 dilutions in 4 cases.6. The bacteriolytic action of the Lysozym contained in the impacted cerumen occurred in dilutions of 1: 10000 to 1: 40000 in 5 cases.7. As above stated, the bacteriolytic action of the Lysozym contained in the pus also took place in dilutions of 1: 150000 to 1: 400000 in 6 cases.