has an important influence: any overloading of the stomach may set up an attack in some persons, but a late meal is especially likely to do it; or particular articles of diet have to be carefully avoided. Constipation and uterine troubles may occasionally act as irritants. Emotion, anger, and fright are instances of cerebral disturbances causing asthma.

Symptoms. Sometimes the attack is preceded by some premonitory indications, such as a general sense of discomfort, drowsiness, gaping, itching under the chin, sneezing and coryza, or the passage of much pale limpid urine. But it is often quite sudden, commencing in the early morning between two and four o'clock, though the patient may have gone to bed apparently quite well. He wakes up with a sense of dyspnoea, so that he has to sit up in bed, or gets out and opens the window to let in more air. The breathing is soon so difficult that he has to call in the aid of all the accessory muscles of respiration; he grasps with his hands the sides of his bed, the arms of a chair, the mantelpiece, or the edge of a table, to give a fixed support for the muscles which pass from the upper extremities to the chest. The chest, however, is nearly fixed in a condition of inspiration, and there is very slight movement. The respiration is often quite slow, but occasionally rapid; the most noticeable feature is the extraordinary length of expiration, which is accompanied with a loud wheezing audible at a distance. The chest is somewhat over-resonant; the inspiratory murmur is scarcely audible, or accompanied with a little sibilant rhonchus, while with expiration is heard the loud rhonchus just mentioned. With this the patient's distress is very great; the face gets cyanosed, the eyes are prominent, the conjunctivæ suffused, and the whole attention of the patient is absorbed in the attempt to get a proper interchange of the air in his chest. Usually there is no pyrexia. After a time-it may be two or three hours-he begins to cough, and expectorates some thin, transparent mucus, which may be mixed with a little blood; then the breathing becomes easier, the cyanosis is less, gradually the whole trouble subsides, and the patient falls off to sleep.

The sputum often contains, besides cylindrical or ciliated epithelium, two peculiar constituents, namely, Curschmann's spirals, and octahedral crystals. The former are yellowish-green or gray particles, made up of threads of mucus; under the microscope they are seen to be spirally-twisted fine or coarse fibres, and there is often in the middle one fine transparent fibre. The octahedral crystals may be present in the spirals; they are the same as Charcot's crystals found in leukæmic blood, and consist of a phosphate of some organic base.

Each attack may last from two or three hours to as many days; their recurrence, at longer or shorter intervals, is a good deal determined by the exciting causes; that is, a careful patient, who knows how to avoid what will bring on his attacks, may escape for long periods. As to the duration of the illness, that also is very variable. Many of those who have it in childhood

recover in adult age; but those who acquire it in middle age never recover. The attacks themselves are rarely fatal, and the occasional occurrence of not very severe attacks is not prejudicial to health; but frequent paroxysms induce emphysema of the lungs, and ultimately attendant bronchitis, so that there is constantly more or less lividity, with the round shoulders, barrelshaped chest, and labored respiration which are observed in the midst of the paroxysms themselves. Life is thereby shortened, and the tendency to suffer from the severer forms of bronchitis is increased.

Pathology. The attacks are clearly attributable to some obstruction of the minute bronchial tubes, and the prevailing view is that this obstruction is due to spasmodic contraction of the bronchial muscular fibre; hence the name "spasmodic asthma," by which it is distinguished from the popular use of the term asthma for every kind of dyspnoea, especially chronic bronchitis and emphysema. But the disease has also been attributed to vascular swelling of the bronchial mucous membrane (fluxionary hyperamia of German authors), and, by Sir Andrew Clark, to a kind of erythematous swelling, occurring in patches over the mucous membrane of the bronchi. The sudden development of the symptoms and the comparatively rapid subsidence in many cases are in favor of its spasmodic origin.

Treatment.-Climate is one of the first things to be considered. A large number of patients can live in London and large cities free from paroxysms, who have them at once if they attempt to live in the country. Conversely, some can only live in the country, and have asthmatic attacks in town. In the same way sea-air may excite attacks in some, and cure others. The facts with regard to any patient can only be ascertained by experiment.

Moderation and care in diet are the next points to consider. Food should be light and easily digestible; a heavy supper should not be taken; and particular foods should be excluded from time to time, such as cheese, pastry, pork, beer, to see if there is any one offender in this respect. If the trouble cannot be met in these ways, and the naso-pharynx presents no lesions for surgical treatment, potassium iodide should be given in doses of from 5 to 10 grains three times a day, continuously and irrespective of the attacks, for some weeks or months. A number of remedies have been used in the attacks, and many of them are decidedly effectual in lessening the severity of the dyspnoea, and shortening the paroxysm. The most useful seem to be those which are inhaled, and so possibly act directly upon the bronchial tubes. The vapors of chloroform, ether, nitrite of amyl, iodide of ethyl, and turpentine may thus be used; but more lasting results are often obtained by the fumes from burning a paper saturated with nitre-solution and dried, or by smoking cigarettes made of chopped stramonium-leaves, or by the use of other preparations containing stramonium. Some similar drugs may be given internally, such as nitro-glycerine, and nitrite of sodium-which also

paralyze organic muscular fibre, and chloral, morphia, extract or tincture of stramonium, belladonna, or lobelia. Two or more remedies may be combined. Local applications may give some relief, such as mustard plasters or turpentine stupes, and, according to some, the application of iodine tincture on the side of the neck, over the course of the pneumogastric nerves. In chronic cases which resist treatment, general tonics, like quinine, or codliver oil may be of value, and the patient should be careful not to expose himself unduly, in view of the secondary changes in the lung which supervene.

DISEASES OF THE LUNGS.

EMPHYSEMA.

The term emphysema (from ¿v, in, and çũʊa, wind) is rightly used to denote the extravasation of air into the subcutaneous or other tissues of the body (surgical emphysema), and into the interlobular or interstitial tissue of the lungs (interstitial emphysema). It is much less applicable to the disease of the lung now under consideration, for which, however, in medical parlance it is usually reserved. The alveoli of the lung naturally contain air; in this disease they are abnormally distended, and may be said to contain too much. So far the name emphysema (vesicular emphysema) may be justifiable, but a more correct name would be that of alveolar ectasis, which has been recently suggested.

Anatomy. The essential change in emphysema of the lungs is a loss of elasticity, from weakening, and subsequent atrophy and destruction, of the elastic tissue contained in the alveolar septa. In consequence of this the walls of the air-vesicles yield to the pressure of the contained air and become distended. This brings them into closer contact with neighboring alveoli which are also dilating; and between the two the alveolar septum becomes atrophied. Soon a perforation is established through the septum between the two alveoli, then the whole septum is destroyed, and the two alveoli become one. In this process not only the elastic tissue, but also the whole network of pulmonary capillaries contained in the septum, disappear. If this is repeated extensively throughout the lungs, firstly, all the air-spaces are much enlarged, and in many places great blebs of lung tissue simply containing air are formed; secondly, the elasticity of the lung necessary for expiration is reduced much below the normal; thirdly, the vascular area available for aerating the blood is greatly diminished; and fourthly, in most cases the lungs themselves are considerably enlarged. A lung affected with emphysema does not collapse when the chest is opened at the post-mortem examination, but bulges out even through the ribs. It is soft and inelastic,

and yields to the pressure of the finger ("pitting"). In different parts of it, especially along the inner or lower edges, may be seen large blebs the size of peas or nuts; and the lung is unusually pale and bloodless, and of a mottled gray color. On section the larger blebs collapse, and the whole. organ is much drier than usual, except in some parts, such as the bases, which may have been the seat of a complicating bronchitis or oedema.

A variety (small-lunged emphysema) occurs in which the lung is not enlarged, and blebs are not numerous. The septa have atrophied so that alveoli have joined together, and the lung is simply inelastic, drier and paler, and presents a less perfectly spongy structure than normal.

Etiology and Method of Production.-No doubt many cases of emphysema result from bronchitis, and some from whooping-cough or asthma, but this will not account for all, as it is certainly common to find the indications of a slight emphysema in those who have never had any such illness.

It rather seems in many cases to develop with advancing age as a senile change; but it may be more directly induced by a number of laborious occupations which entail prolonged strain upon the lungs, the chest being held full of air for a long time either to serve as a point d'appui for the use of the arms, or to supply air in a regulated way, as in playing upon wind instruments, glass-blowing, etc. In all cases it is the failure or wearing-out of the elastic tissue that is the essential lesion; it may wear out from age or from exceptional strain at an earlier period; though emphysema is sometimes found in young people whose circumstances do not seem to be exceptional.

The mechanism in the case of glass-blowers, etc., is probably that the lungs are kept expanded during the regulated effort, or that the force of expiration is opposed by the obstruction in the work, and so the elastic. tissue is kept unduly on the stretch. Prolonged coughing has the same effect in bronchitis and whooping-cough; and in the former the secretions constitute an obstruction to the expiration, from which the elastic tissue necessarily suffers strain. The greater development of emphysema at certain parts of the lungs, especially the anterior margins and lower edges, and in the neighborhood of old cicatrices at the apex, may be accounted for on Sir William Jenner's view-that when air is retained in the chest under great pressure, as when playing a wind instrument, or making any great muscular effort, it is the parts of the lung which are least supported by the surrounding structures outside which will be most subject to the air-pressure from within. These are precisely the anterior lower edges in healthy lungs; and when a portion of lung shrinks from old disease, the support of the adjacent lobules is, of course, withdrawn.

Results of Emphysema.-These are of two kinds. In consequence of the loss of elasticity, expiration, which is largely effected by the sponta

neous collapse of the lungs after inspiration, becomes more difficult; the lungs tend to increase in size; the chest enlarges in width and depth, assuming permanently the shape and position which are characteristic of full inspiration; the mobility of the chest, and hence the interchange of gases, is much diminished, since it ranges only between different degrees of inspiration, instead of between full inspiration and full expiration; the effects of every attack of bronchitis are aggravated from the impairment of coughing power which follows on the above defects.

The other important factor is the loss of capillary area, and hence of aerating surface. From this results an obstruction to the pulmonary circulation, of a kind similar to what is produced by disease of the left side of the heart. The tension in the pulmonary artery and right ventricle is increased, the right ventricle hypertrophies or dilates, or both, and the venous system becomes engorged, producing, in course of time, congestion and enlargement of the liver, oedema of the feet, legs and trunk, and albuminuria. Symptoms and Physical Signs.-The symptoms of emphysema are at first only shortness of breath: the cough and expectoration which are commonly present result from a coexisting bronchitis. The dyspnoea is especially seen on exertion in early stages, when the breathing is quickened and the patient readily pants; later on, it may be always present, producing orthopnoea at night. In its worst forms the extraordinary muscles of respiration are in constant use; the clavicles are lifted, and the sterno-mastoids and scaleni stand out at each inspiration, striving to increase the tidal air; expiration is prolonged, labored and aided to the utmost by the muscles of the abdomen. The physical signs are characteristic. The chest is broad, deep antero-posteriorly, but short; it is often called barrel-shaped, from its enlargement, and from the increase of the antero-posterior diameter giving it a circular instead of a transversely oval shape. The shoulders are raised; the upper ribs are closer together, and the lower ribs wider apart than normal; and the epigastric angle is very obtuse, measuring 150° or more. The elevation of the ribs alters the relative positions of the nipple and the heart's impulse: the nipple is often found on the fifth rib, and the heart's impulse in the sixth space. But this last may be partly displaced by the enlarged lung. Percussion gives excessive resonance over the parts of the chest that are normally resonant, and an extension of the resonance over areas that are normally dull. Thus the hepatic and cardiac dullnesses are encroached upon, the right lung being resonant down to the sixth space or seventh rib, and the heart-dullness being limited to the fifth cartilage and space below, or even disappearing altogether. Posteriorly, the dullness extends to its fullest limits downward. On auscultation the inspiratory murmur is very much diminished or scarcely audible, and the expiratory murmur is much prolonged. The enlargement of the lungs also affects the signs connected with other organs.