The tongue also is not infrequently a hindrance to the formation of a good tone, especially when the pupils have not been taught early enough to open their mouths sufficiently wide. When the high tones are to be produced, which require much room in the forward part of the mouth, the tongue is usually drawn back and raised, in order to make the necessary room within the lower front teeth. This, again, is a habit difficult to be broken, and care must be taken that the lower front teeth are lightly touched by the tip of the tongue in singing, in order that the tongue may be accustomed to a natural position. But this is most easily attained when the tongue is at the first kept occupied as much as possible by quick exercises with the syllables of solmisation, or by practising tones in slow time upon syllables beginning with consonants formed by the tip of the tongue. As in pronouncing the German _Sch_ the tongue presses the teeth all around with its outer edge, syllables formed with these consonants serve excellently well to accustom the tongue to a quiet, correct position. FLEXIBILITY OF VOICE We hear it continually said that it requires a special natural gift to acquire a certain ease and flexibility of voice, and that this natural gift is peculiar to the Italians. But the flexibility of the voice depends upon a physiologico-physical process of the organ of tone, which, among the Italians, goes on in their common speech, and hence is more easily transferred by them to their singing. In trills, roulades, turns, and all tones quickly succeeding one another, the breath must set the vocal chords vibrating in quick, short pulses. The little time used by the breath between these rapidly succeeding pulses to retreat, in order to give another pulse, suffices perfectly to produce easily and quickly the position of the glottis requisite for a higher or lower tone. In order, between the pulses, to give room to the retreating breath, the windpipe expands laterally, whereby the larynx is always somewhat drawn down, in order, with the next pulse of the breath, to take again its former place. This rising and lowering of the larynx can be seen plainly outside the throat, and it can be seen also whether the movement goes on rightly. Upon the degree of rapidity with which this movement goes on depends the greater or less flexibility of the voice.