take care not to wound the large veins, and thus fill the pleural sacs with fluid or coagulated blood, rendering it impossible to determine their other contents.

We have not one thoracic cavity but two separate pleural sacs and pleural cavities, a pericardium and pericardial cavity. In opening the pleural sacs, note the position, color, etc., of their contents, amount and character of the fluid, presence of a foreign body, of adhesions, wounds, etc. Ascertain the existence of hæmatothorax, hydrothorax, and pleuritis, and leave the lungs and pericardium for subsequent observation.

The lungs should not be removed from the thorax before the heart has been examined, for the pulmonary artery and veins will be separated from them, and the left auricle, trunk of the pulmonary artery, and the right ventricle will be partially emptied.

THE HEART.-Open the pericardium by a vertical incision, examine its condition, amount of fluid, the appearance, position, size (atrophied or hypertrophied), shape, consistence (fatty, etc.) of the heart, amount of blood in the superficial vessels, and of fat in the sub-pericardial areolar tissue. Then open the heart in situ, to determine at first the quantity of blood in the cavities and the capacity of the auriculo-ventricular orifices, especially of the left side. Deaths from asphyxia and paralysis of the heart probably occur from overfilling, in the first case, of the right ventricle, in the second of the left. To determine the sufficiency or capacity of valves, all the parts belonging to the auriculo-ventricular valves, the chorda tendineæ and musculi papillares, must be retained in their integrity. As the base of the heart must be preserved, on account of the attachment on the two sides respectively of slips. of the tricuspid and mitral valves, and as each auricle and ventricle must be examined separately, four distinct in

cisions are necessary. In case it should not be expedient to remove the heart, a tolerably complete examination may be made according to the following brief directions:

1. To examine the right ventricle, carry the incision from close to the base of the right border of the heart, deeply and forcibly into the interior of the ventricle, bringing the knife out towards the apex, without going down so far as to wound the septum. This incision is a guide for the three others, the place for each incision being found in a plane taking the direction of the first.

2. To examine the right auricle, commence the incision half way between the places of entrance of the venæ cavæ, and let it end close to the base.

3. To examine the left auricle, the incision should commence at the left superior pulmonary vein, and end close to the base, as indicated by the prominent coronary vein. The coronary vessels should not be injured.

4. To examine the left ventricle, begin the incision close. below the base, carry it deeply and forcibly through the wall of the heart, and let it end just short of the apex.

The heart is brought into proper position for examination of the right side, by pushing the firmly extended left forefinger under the organ, and keeping it against the base, so that the ventricular portion hangs down over the forefinger. Then turn the heart on its axis towards the left until the right border presents anteriorly, press the left thumb just behind this border at the base, and make, one after the other, both the incisions for the right side, as above described.

To examine the left side, draw the apex upwards and to the left, and place the heart encircled in the fingers of the left hand. By gentle pressure, make the posterior wall to bulge out a little, and withdraw itself from the septum.

21

Then make the incisions for the left side as above described.

After making the incisions in the right side, remove and examine the quality and quantity of blood from the right auricle; then insert the left index and middle. fingers from the auricle through the tricuspid opening into the ventricle, and endeavor to open this latter cavity. Remove the blood from the right ventricle, determine it as before, and do the same on the left side. Do not examine the valves at this stage, as adhesions, coagula, etc., may be disturbed. The contracted condition of the left side of the heart must be borne in mind, but this contraction, with the rigor mortis, may be overcome by gentle pressure.

To remove the heart, introduce the left index finger into the left ventricle, and the thumb into the right, through the already existing incisions; raise up the apex, and with it the whole of the heart, and with three or four long, free, horizontal incisions, made not too close to the heart, divide the vena cavæ, the pulmonary veins and artery, and the aorta, all together. After removal, examine the cut openings of the aorta and pulmonary artery, the size of these vessels, the thickness of their walls, and remove any and all coagula. Examine the capacity for closure of the arterial orifices by pouring water into the aorta and pulmonary artery, holding the heart freely sus pended in the air, so that the orifices will not be closed or the walls compressed by pressure of the hand. The points of the fingers should be applied to the vessels to be examined, or externally near the base of the valves, so that the plane of the orifice shall be exactly horizontal, and not drawn to any side. To prevent dragging, stretching, or valvular closure, both hands must be used,

to support the heart properly, and the water must be poured in by a second person.

In examining the aortic orifice, apply the tips of the fingers closely around it on the right and left auricles and pulmonary artery; for if applied simply to the edges of the aortic opening, the parts may be stretched unequally, and besides we have to divide the aorta again at a distance of four or five centimetres above the orifice by an incision parallel to the plane of the aperture. If the coronary arteries were divided when the left side of the heart was first incised, the water poured in may escape through them. In the case of the pulmonary artery it is different, and to test the pulmonary orifice the heart can be suspended by fixing between the fingers the edges of the opening into the vessel.

For thorough examination of the heart, after removal, place it exactly in the position it occupied in life, on a board or table. The parts to be examined are the auriculo-ventricular valves, with their chorda tendineæ and musculi papillares, the cavities themselves, their endocardium, the arterial valves, auriculo-ventricular septum, and muscular substance.

For the right ventricle, the incision is made in a straight line prolonged from the pulmonary artery, and near the base of the heart, with a long pair of scissors; one blade being inserted into the previous incision in the right border (p. 321), and carried towards the pulmonary artery, care being taken, by introducing the blade in front of the papillary muscle, and carrying the incision close to the base, not to cut through the muscle of the tricuspid valve with its chorda tendineæ, which would interfere with the demonstration of the tricuspid valves.

For the left ventricle, the incision, with similar scissors, is in a straight line prolonged from the ascending aorta,

and close to the septum ventriculorum; commencing at the apex and dividing the anterior wall of the ventricle and of the aorta. Care must be taken not to divide the base of the mitral valve. Avoid cutting through the valves of the pulmonary artery by drawing that vessel to the right when making the incision, and by continuing this to the left, close to and behind the artery; not too far to the left, as the right border of the base of the mitral valve is inserted quite close to this spot, and this valve is connected immediately with the left border of the aortic orifice. If the incision goes only a few millimetres too much to the left, that portion of the mitral valve will be cut off which forms this junction, and the result will be an aperture in that valve when the divided portions of the heart are put in apposition. Externally this spot corresponds exactly with the right border of the base of the left auricle, and should be the guide, the incision being carried through midway between the pulmonary orifice and the left auricle.

This completes the examination of the heart-all of which can be done in ten minutes-unless it be desirable, in exceptional cases, to open the auricles by cutting through their wall with the scissors, between the openings of the vena cava on the right, and of the pulmonary veins on the left side; or to make further incisions in the muscular substance or the coronary arteries.

THE LUNGS.-In examining the lungs we must take care not to injure the root, where the vessels, nerves, and excretory ducts occupy important relations, as it may be necessary to probe, dissect, inject, or use the blowpipe in the vessels or canals. As already stated, the lungs should not be removed until after the examination of the heart. Should it be desirable to remove the lungs and heart together, tie the trachea and vessels to