The nose, however, has a much more important function to perform--viz., in respiration. Strange to say, however, this has only recently been realized, and it is even yet not well understood. You have all observed that, when you had a severe "cold" which prevented nasal breathing, the next morning the mouth and throat were dry and parched and frequently inflamed, the voice sometimes hoarse, and there was a general feeling of depression. While the progress of the inflammatory process may be a factor in this, still the mechanical obstruction of the nose from any cause whatsoever will have a similar effect. In patients in whom, for various reasons, an artificial opening has been made in the trachea, the air of the room has to be heated to an almost intolerable point and saturated with moisture, or severe bronchial inflammation will soon develop in the patient, simply because the nose has not taken an active part in the act of respiration. These effects, therefore, clearly demonstrate that the nasal passages have an important function to perform in the breathing process. Summarized in a few words, it is simply to warm, moisten, and clean the air which we inhale. The healthy nostrils are anatomically and physiologically so formed that when the current of air passes through them it will have been freed of its mechanical impurities, warmed to within a few degrees of the temperature of the body, and moistened to saturation. This has been experimentally demonstrated. The opening of the passage of the ear into the throat has several objects, the most important being ventilation and the adjustment of the atmospheric equilibrium. This passage leads outward until it enters the cavity of the middle ear, which is closed by the drum on the outside, thus separating it from the external canal of the ear. We know that atmospheric pressure varies at different times and in different altitudes. It is much less, for instance, at the top of a mountain than at the seaside. The opening into the throat allows the air to enter, and adjusts the atmospheric pressure within the ear to these various external conditions. Those of you who have ascended Lookout Mountain by means of the incline cable car may have noticed the adjustment taking place by a peculiar click when different altitudes were reached.