a minor third, major third, fourth, etc., by which first the upper, then the lower tone is accented: accented-a¹ g¹ a¹ accented-g¹ a¹ g¹. The mouth, however, in this exercise must continue immovably open, and the tongue also must lie perfectly still, touching the lower front teeth, for only in this way can one be sure of not moving the epiglottis. Although this is difficult at first, yet the syllable _ku_ (koo) may be sung in this way. Thus, with sufficient practice, any one may acquire a perfect flexibility of voice. When the pupils can make the trill easily upon the middle tones, in which in the beginning exercises must be practised, let them practice also upon the higher and lower tones of the voice. If the trill takes place at the transition of two registers, then both the tones must be formed upon the higher of the two, as in an exchange of registers the glottis requires more time than a good trill admits of. Rapid runs downwards are easily executed correctly when care is taken that with every tone the same movement is made as in the case of trills, and the breath is kept back as much as possible. Voices wanting in flexibility may soon acquire the desired quality by singing every tone _piano_ upon the syllable _koo_. Ascending runs can properly be taught only when the descending have been correctly sung, for, in opposition to the former, every tone of the latter must be formed by a light impulse with increased breath. The softer the piano in which the pupil practises, and the more loose the consequent movement of the larynx, the more distinctly and the more purely will the pupil gradually execute these embellishments.