The =Cavities of the Nose= (pl. I, N), which have for their base the hard and soft palate (pl. I, H and S), and which are divided by a bone partition. The only part of the =Mouth= which requires a particular description is the soft palate. This is a movable partition by means of which either the mouth or the nose can be completely separated from the throat. If the nose is to be shut off from the throat the soft palate is _raised_, and pressed against the back of the pharynx. If the mouth is to be shut off the soft palate is _lowered_, and rests closely upon the back of the tongue. This partition plays a most important part in vocalization. In the formation of all pure vowel sounds it is _raised_, thereby closing the nasal cavities, and it has been found that the closure is loosest for "ah" (as in "father") and tightest for "e" (as in "bee"), the intermediate vowels being "a" (as in "name"), "oh" and "oo" (as in "food"). This has been clearly shown by Czermak in the following manner. Lying down on his back, he had the nasal cavities filled with tepid water. He then uttered the various vowel sounds, and ascertained from the quantity of water required to force open the closure formed by the soft palate the degree of tightness for each vowel. He afterwards constructed a very ingenious little apparatus, by means of which, in one of his lectures, he demonstrated this fact to his audience. It will be easily understood from the above explanation that, if the closure of the nasal cavities is sufficiently imperfect to allow any considerable amount of air to pass through the nose, the result will be a nasal tone.