Consonants may also be divided into the explosive, which are of momentary duration; such are ↳, p, d, t, r, and hard g; and the continuous, which are more like the vowels, the breath being imperfectly interrupted.

STAMMERING.

A few remarks on stammering here. Stammering is due to a continued or rapidly-recurring spasm of some muscle or muscles engaged in speech, in consequence of which it is either suddenly brought to a complete standstill, or some sound is rapidly repeated. The spasm generally occurs at the beginning of words, and implicates the consonants, especially the explosives (b, p, d, t, k, and hard g), more than the vowels. It most frequently convulses the lips (when the labial sounds are arrested) or at the top or base of the tongue; but it may also involve the inspiratory and laryngeal muscles.

We shall the better understand how such spasm may occur if we keep in mind that the muscular mechanism. of speech is highly complicated, requiring not only that the breath be driven with sufficient force through the larynx, and the chords properly acted upon by the laryngeal muscles, but also that the soft palate, lips, and tongue, be appropriately adjusted. These several acts must all be in harmony-their co-ordination, as the physiologists term it, being effected by the nervous system, and seeing that the utterance of every sound requires its own special muscular adjustments, which during speech must therefore be ever changing with

extraordinary rapidity, there is ample opportunity for the machinery to break down, and this is what happens in stammering. The nerve-centres which govern the articulatory muscles run riot.

Stammering generally begins in childhood, and is most common in those of defective nervous organization. It is not infrequently started by fright or by a severe illness, and in all cases illness renders it worse; indeed the health of the stammerer can generally be gauged by the degree of his stammering. Stammering can usually be cured by suitable treatment.

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ON THE DIFFERENT METHODS OF

BREATHING.

DURING phonation the breath is urged somewhat sharply through the glottis, the vocal chords being in this way vibrated, and not the least important part in

THORAX OR BONY CAGE OF THE CHEST (NORMAL).

Showing the graceful curves of the thorax and the increasing capacity from above downwards.

voice-production is the proper management of the breath. This we will now consider.

The bony framework of the thorax, or chest, consists of the vertebral column, the breast-bone, and the ribs, as shown in Fig. 16. The ribs, twelve in number, arc

fixed behind to the vertebral column by a hinge-like arrangement, which permits them to move up and down; in the front the seven upper ribs are attached to the sternum, the next four are united to one another, so constituting part of the "costal arch," while the last two are free anteriorly, and have therefore been termed the "floating ribs." The thorax is open above to allow the passage of important structures between it and the neck, while below it is closed by a muscular partition called the midriff, or diaphragm, which is shaped somewhat like a dome with its convex surface upwards.

The lungs are accurately fitted into the thorax. During inspiration this cavity enlarges, and the lungs, being compelled to remain in contact with the chestwalls, expand. The air within them thus becomes rarefied, and fresh air rushes in to fill the partial vacuum. During expiration, on the other hand, the chest cavity contracts, the lungs are compressed, and a certain quantity of their contained air is expelled.

We have now to inquire by what means the thorax is made to vary in size. During inspiration the ribs move upwards on their hinge-joints behind, carrying the breast-bone with them, while at the same time the dome-like diaphragm flattens. This movement of the ribs causes the chest to increase both in depth and width, as may readily be proved by placing one hand on the front and the other on the back of the chest during a deep inspiration, when they will be found to move further apart; the same happening if the hands are placed on either side of the chest. The flattening of the diaphragm causes the chest to increase in

height; and its movement may be rendered evident by placing the hand on the front of the abdomen during a deep inspiration, when the abdomen will protrude owing to the descending midriff thrusting certain organs downwards.

Inspiration is, therefore, a muscular act, requiring some effort, especially when deep. Expiration, however, is, under ordinary circumstances, purely passive, being brought about by a mechanical recoil: a, of the elastic lungs, which during inspiration are stretched, and consequently tend to contract when the inspiratory forces cease; b, of the ribs, which, during inspiration, are bent (much as a piece of whalebone might be), and which resume their wonted position upon the removal. of the pressure; c, of the abdominal contents which oppose, as it were, an elastic buffer to the descending diaphragm.

The difference between active deep inspiration and passive expiration may be tested by the reader for himself. A distinct sense of effort will attend the one, but will be quite absent from the other. All that is necessary in the latter case is to cease to act upon the - inspiratory muscles, the air being driven out independently of the will. But while under ordinary circumstances expiration is a merely passive act, it is yet under the complete control of the will. For not only can the air be forcibly driven out of the chest by a contraction of the muscles which depress the ribs and of the abdominal muscles which, by compressing the abdominal viscera, forcibly drive the diaphragm upwards, and so expel the air from the chest, but it can be let out very gradually by preventing the