ment,*-physical signs, like the whole class of objective phenomena of disease, are of materially greater clinical value than its subjective symptoms. Physical signs are, then, the true indices of the nature, extent, and degree of organic textural changes, and may be regarded as instruments of pursuing morbid anatomy on the living body. But just as their significance is sure and precise, so is the difficulty of mastering their theory and practice positive and great; and hence it is that Physical Diagnosis has gradually acquired for itself the importance of a special art. The means by which the existence and nature of physical signs are discovered, are called Physical Methods of Diagnosis; and these methods vary with the properties, position, and functional relations of the organs examined. The diseases of the organs of respiration and of circulation are those of which the physical signs are best understood and most readily ascertained; the methods employed in their detection are:—

I. INSPECTION; II. APPLICATION OF THE HAND; III. MENSURATION; IV. PERCUSSION; V. AUSCULTATION; VI. SUCCUS

SION.

These methods are, as nearly as is possible, applied to the organs themselves of which we desire to ascertain the condition, -to the external surface corresponding to them, when inapplicable to themselves. But the absence or presence of disease in the different thoracic organs, and, if it exist, its nature, may *sometimes be indirectly inferred by employing these methods in

VII. THE DETERMINATION OF THE SITUATION OF SUrroundING PARTS AND ORGANS,-which may consequently be considered an additional method of physical diagnosis.

All these methods agree in the general character of their direct and indirect objects. The direct object, the physician has in view with all, is the just appreciation of the sensations they furnish, and these are nothing more than the physical signs already spoken of; the indirect object, the reference of these signs to the material states upon which they depend.

The general description of each of these methods must comprehend an inquiry into:-Its nature; its direct or immediate

* In the present state of knowledge it must be confessed that physical signs directly reveal only physical conditions; but it is very probable that in time they will reveal the nature of disease too. The fundamental sounds of lung, in situ, solidified by cancer, by tubercle, or by simple exudationmatter, for instance, cannot be the same; though by the percussor of the present day no special difference can be caught.

object; the manner of practising it; the conditions which are discovered by its means in the healthy state; such deviations from the ordinary standard of these conditions as are, nevertheless, compatible with health; the deviations from that standard which are actually morbid and constitute signs of disease.

Diagram exhibiting the anterior regions of the chest, with their relationship to the ribs and also the position of the edges of the lungs in calm (phrenic) respiration. 1 to 10 inclusive, ribs; a, supra-clavicular region; b, clavicular region; c, infra-clavicular; d, mammary; e, infra-inammary; f, supra-sternal; g, upper sternal; h, lower sternal; i, trachea; k, integuments. The dotted lines indicate the boundaries of the various regions; the thick lines correspond to the outlines of the lungs, which rise to a maximum height of one inch and a quarter above the clavicle; (at the apex the outer border is carried to the line of full inspiration;) ++, the nipples. Taken from an adult male, the trachea being tied after moderate insufflation of lungs.

With the view of localizing physical signs as precisely as possible, the surface of the chest has been divided into artificial regions; but as the assignment of limits to these regions is

altogether arbitrary, it is not to be wondered that the boundaries adopted by different writers vary. Simplicity, as far as is compatible with the main object, should be especially aimed at in all such topographical arrangements; but it scarcely appears possible, without a sacrifice of utility, to make the number of divisions less than in the following plan. They are designed to correspond, as far as is attainable, with important internal regions or outlines.

The chest is divided into anterior, lateral, and posterior regions. The anterior are called: supra-clavicular, clavicular, infra-clavicular, mammary, infra-mammary, supra-sternal, upper sternal, lower sternal. The lateral regions are: the axillary, the infra-axillary. The posterior series comprises: the upper scapular, the lower scapular, the infra-scapular, and the interscapular. Of these regions the supra, upper and lower sternal are single; all the rest are double.

The boundaries of these regions, and the more important structures and portions of organs corresponding to them, either within the chest or on its confines, may be stated as follow:

Supra-clavicular.-Above, a line drawn from the outer part of the clavicle to the upper rings of the trachea; below, the clavicle; inside, the edge of the trachea. Here are found the triangular apex of the lung, portions of the subclavian and carotid arteries, and of the subclavian and jugular veins; the first rib contributes to form a sort of floor for the region.

Clavicular.-Corresponds in its outline to the inner half of the clavicle. Beneath the bone lies on both sides lung-substance: on the right side (at the sternal articulation) the arteria innominata just reaches the inner confines of the region, while the subclavian artery crosses it at its outer end; on the left side the carotid and subclavian arteries lie deeply, almost at right angles with the bone.

Infra-Clavicular.-Above, the clavicle; below, the lower border of the third rib; outside, a line falling vertically from the acromial angle (formed by the clavicle and the head of the humerus;) inside, the edge of the sternum. Within these limits. are placed the upper lobe of the lung, on both sides; on the right side, in addition, the superior cava, and a portion of the arch of the aorta; on the left, the edge of the pulmonary artery. The vessels on both sides lie behind the costal cartilages of this region; and the second right cartilage may be familiarly termed the "aortic" cartilage, the second left the "pulmonary." On

the left side, the inferior border of this region corresponds to the base of the heart. The bifurcation of the trachea taking place behind the arch of the aorta, on the level of the second rib, the main bronchus on either side is found in this region, the right behind, the left a little below, the second costal cartilage. Mammary.-Above, the lower border of the third rib; below, the sixth rib; outside, a vertical line continuous with the outer border of the infra-clavicular region; inside, the edge of the sternum. The contents of this region differ materially on the two sides. On the right side, the lung lies throughout immediately under the surface, extending downwards to the sixth rib, where (its inferior border lying almost horizontally) it nearly corresponds to the lower edge of the region. The right wing of the diaphragm and the liver commonly rise to the fourth interspace. The line of separation of the upper and middle lobes of the right lung passes obliquely upwards and backwards from about the fourth cartilage; that of the middle and lower, in this direction from the fifth interspace. A portion of the right auricle and the upper and right angle of the right ventricle lie between the third and fifth ribs, close to the sternum. On the left side, the edge of the lung passes obliquely downwards and outwards from (usually) the fourth cartilage, leaving a free space of variable size for the heart,-thus reaches the fifth rib, then curves inwards and downwards to opposite the sixth rib or interspace (within the vertical line of the nipple,) whence it passes nearly horizontally outwards. The anterior point of division of the lobes of this lung lies about the fifth interspace, below the nipple. The left auricle and left ventricle, with a small portion of the right ventricle about the apex, lie within this region.

Infra-Mammary.-Above, a line slanting outwards from the sixth cartilage; below, a curved line corresponding to the edges of the false ribs; outside, the outer edge of the mammary region prolonged; inside, the sternum at its inferior angle. On the right side the liver (with the lung protruding in front on full inspiration) occupies this region. On the left side lie the stomach and anterior edge of the spleen, which rises as high as the sixth rib; in the inner part of the region there is generally a portion of the left lobe of the liver, lying in front of the stomach.

Supra-Sternal.-A small region, more or less hollow, bounded below by the notch of the sternum, and laterally by the sternomastoid muscles. The trachea fills it almost completely; it contains no lung; the innominate artery lies at its lower right

angle; and in some persons the arch of the aorta reaches its lower border.

Upper-Sternal.-Corresponds to that portion of the sternum lying above the lower border of the third rib. Here are found the left (and a small portion of the right) innominate vein; the ascending and transverse portions of the arch of the aorta; the pulmonary artery, from its origin to its bifurcation; the aortic valves, near the lower border of the third left cartilage,-the pulmonary a little higher than these, and quite at the left edge of the bone; and the trachea, with its bifurcation on the level of the second ribs. The inner edges of the lungs, coming slantingly downwards, usually almost join on the middle line opposite the same ribs, and continue thus united for the rest of the region, lying immediately under the sternum.

Lower-Sternal.-Corresponding to the remainder of the sternum, this region contains the main part of the right ventricle, and a small part of the left; the line of union of the heart and liver (with the diaphragm intervening;) the edge of the right lung descending vertically along the middle line, and, at its upper part, a small portion of the left lung; and inferiorly, and deeply-seated, a portion of the liver, and sometimes of the stomach. The tricuspid and mitral valves (the latter somewhat posterior) lie at mid-sternum opposite the upper edge of the region, or a little below this.

Axillary.-Extending from the point of the axilla above, to a line continuous with the lower border of the mammary region below, and in front from the posterior border of the infra-clavicular and mammary regions to the external edge of the scapula behind, this region corresponds to the upper lobes of the lungs, with, deeply-seated, the main bronchi.

Infra-axillary.-Bounded above by the axillary region, anteriorly by the infra-mammary, posteriorly by the infra-scapular, and below by the edges of the false ribs, this region contains on both sides the lower edge of the lung sloping downwards from before to behind, with, on the right side, the liver, and, on the left the spleen and stomach.

Upper scapular and lower scapular.-Have the same boundaries as the fossæ of the scapula, and correspond to lung-sub

stance.

Infra-scapular.-Above, the inferior angle of the scapula and the seventh dorsal vertebra; below, the twelfth rib; outside, the posterior edge of the infra-axillary region; inside, the spine.