fications end in tiny pouches or "air-cells," which the unscientific reader may picture to his mind's eye as. resembling soap-bubbles of infinitesimal size. Each "bubble," or cluster of "bubbles," communicates through a minute opening with the ultimate divisions of the bronchial tubes. The walls of these little cells are very thin and of highly elastic structure, and in the substance of each is a delicate network of very small blood-vessels, called "capillaries." It is here that the vital part of the respiratory process, viz. the purification of the blood, takes place. This consists essentially in an exchange of gases between the blood and the air, whereby the former yields up the waste matters of the system in the form of carbonic acid, receiving in return a fresh supply of oxygen. It is evident from this how important it is to have a sufficient supply of pure air, i.e. air which contains its due proportion of oxygen, to renovate the blood. A room in which a number of people are sitting soon becomes "close" if the windows and doors are kept shut: this indicates that the oxygen in the air is exhausted, its place being taken by carbonic acid exhaled from the lungs of the assembly, so that the purification of the blood must necessarily become more and more imperfect. process of re-breathing air that has already been used, if long continued, leads to asphyxia and death, but short of this point it gives rise to much distress, and even disease. This cause, for instance, lies at the root of much so-called "delicacy,"

This

susceptibility to cold, languor, headache, and nervous depression.

It is not so much, however, the physiological as the mechanical part of breathing that I am immediately concerned with. Besides their principal function of purifying the blood, the lungs are the bellows of the vocal instrument. They propel a current of air up the windpipe to the narrow chink of the larynx, which throws the membranous edges or lips ("vocal cords ") of that organ into vibration, and thereby produces sound. The air taken into the lungs in inspiration distends the air-cells; it is driven out again mainly by the contraction of the elastic walls. of the little cells themselves. This is the essential feature of the expiratory act. Inspiration, on the other hand, is more complex, and may be performed in two or three different ways or by a combination of them. They all have the common object of increasing the capacity of the chest so as to leave room for the expansion of the lungs as the air is drawn into them. What may be termed the natural method of breathing is performed principally by the agency of a large muscle known as the diaphragm (Fig. 1, 1, and Fig. 2, d), which spreads across the cavity of the trunk, dividing it into an upper or thoracic, and a lower or abdominal, space. The former is known as the chest ; the latter (to ears polite) as the " stomach." The diaphragm, when in a state of repose, arches upwards, so as to make the floor of the chest a kind of dome, on the convexity of which rest the

bases of the lungs, whilst the under surface looks towards the abdomen. In contracting, the muscle descends towards the latter cavity so as to make the floor of the chest almost flat, thus leaving room for the increase in volume of the inflated lungs. In expiration the diaphragm simply returns to its former.

FIG. 2.-THE VOCAL INSTRUMENT.

7, larynx; t, trachea; br, bronchi; lg, lung; d, diaphragm.

condition. This mode of breathing is known as "diaphragmatic." The action of the diaphragm is assisted by the elevation and partial expansion of the ribs (see Fig. 2), which, together with the breastbone, make a cage-like framework for the chest. Each

pair of ribs is furnished with two sets of muscular fibres which act on them in contrary directions. Breathing carried on mainly by the ribs is called "costal" respiration, and it is sometimes largely practised by women with the upper ribs alone owing to the partial fixation of the lower by tight stays. In very violent breathing the collar-bone (or "clavicle") is forcibly drawn up by the muscles of the neck so as to assist the action of those which act on the ribs. This method of inspiration is called "clavicular." These three modes of inspiration include all the means at our disposal for taking breath, and it is important for all who use the voice to understand them. Clavicular breathing is seldom employed except in certain diseased conditions and during very violent exertion.1 To obtain its full power the hands must firmly hold. some fixed object in order that the collar-bone may (through the shoulder-blade) have a fulcrum. When costal or diaphragmatic breathing is spoken of, it must always be remembered that in the normal human body both methods are always used together, the one assisting and completing the other. The terms are in reality relative, and are, or should be, applied only as one or the other type predominates in an individual at a given time.

The larynx is sometimes absurdly called the

1 The force with which the clavicle may be drawn up is shown by the fact related by Dr. Walshe (Dramatic Singing, London, 1881, p. 15, footnote), that Rubini actually broke his collar-bone in delivering a very high note.

"voice-box,” as if it were one of those ingenious toys which grind out a thin strain of wiry melody on being wound up. If a comparison is necessary, I should prefer to liken it to a hollow wedge, of which the sharp end looks forward. The larynx is, in fact, an expansion of the upper part of the trachea, on which it is placed like a funnel on the top of a tube. The large end, which is uppermost, is provided with a self-acting lid, whilst the lower is continuous. with the windpipe, and through it with the lungs. Almost round at its lower end, the larynx is nearly triangular in shape at its upper opening, the apex, of course, being in front. The walls are formed mostly by pieces of cartilage of various size and shape held together by muscles and other soft tissues, the whole being covered by a smooth, moist integument like the skin lining the mouth, and known as "mucous membrane." The lowest cartilage, i.e. the one immediately above the windpipe, is called the "cricoid" (Fig. 3, cc), and is almost circular in outline. In shape it resembles a signet ring, the broad surface (representing the seal) being at the back. It is usually large enough in circumference to admit a man's forefinger. Above the cricoid is the "thyroid" or buckler cartilage (Fig. 3, tc) which forms the front and sides of the larynx. It consists of two lateral parts or "wings" which are joined together in front at an acute angle, forming a prominence which is visible in the neck as the " Adam's apple." A notch varying in depth in different individuals, but usually more