When found as a sequel of carditis, the softening is of a dark tint, the fibres are dark from the whole heart being gorged with venous blood, soft and loose in their texture, being easily separable, and compressed with facility between the fingers. When accompanying chronic carditis and co-exisiing pericarditis, the white colour predominates, sometimes being nearly superficial, and attended by peri cardial and sub-pericardial effusion.
The yellow-coloured softening is found in cases of local and general anmmia, in malig nant fevers ; and it sometimes has an inflam matory, as well as merely cachectic origin. An abnormal deposition of adipose tissue in the cellular structure of the heart, produces sof tening by affecting the nutrition of the mus cular fibres, vvhich snffer also from the state of system peculiarised by the above deposition.
Induration of the heart is said to follow carditis, and appears to be produced by the effusion of lymph into the cellular tissue, around the muscular fibres and beneath the serous membranes ; by its contraction and sub sequent hardening, it may pass into a sub stance almost equal to bone in hardness. .
It may exist in any part of the organ, the whole of the apex and the columnth carneth of the left ventricle were found indurated in one case, and in another the walls of the ven tricles were tough, did not collapse, and emitted on being struck, a ringing hollow sound. We sometimes find partial softenings and indurations in the same heart.
Softening of the lungs generally depends upon the presence of effused products of in flammation; for instance, in the engorged, he patised, and suppurative stages of acute pneu monia. It is worthy of remark, that, although in the hepatised stage the lungs are heavier, contain less air, and appear denser, still they are more fragile, and on being pressed by the finger break down. The more acute and re cent the inflammation, the greater the soften ing. When we press a healthy lung with the finger, it gives to the touch on account of the elastic state of the tissue ; but this is lost, and an unusual resistance, easily broken through, is produced by the loss of air, and the pre sence of lymph, compound granule cells, se rum, and an abnormal quantity of blood.
In the third stage of pneumonia, softening.
is produced by the alterations in the effused products ; lymph, for instance, is converted into a yellow friable matter, which subse quently becomes pus. In typhoid pneumonia the softening is great, even in the first or con gestive stage.
Softening of the lung may be produced by an insufficient supply of blood. A part of a lobe may be so indurated, that the vessels and bronchial tubes passing through it become blocked up ; the tissue which ought to have been supplied by these becomes at first soft, and finally gangrenous.
Induration may occur in any part of the lung, it may affect simply the bronchi and the tissue in their immediate neighbourhood, or the interlobular cellular tissue and the paren chyma may suffer.
The bronchi after long continued and re peated attacks of inflammation are found in a more or less indurated state, the hardening being generally in the outer cellular coat, and the cartilages of the larger tubes may become as hard as bone. The lung in the vicinity is generally. denser than it should be.
The Interlobular cellular tissue may be hardened at the same time as the lobules, or separately ; it becomes more apparent than usual, and acquires a density occasionally re sembling fibro-cartilage, and sometimes exer cises so compressing an influence on the lobules, as to obliterate them.
But it is as a sequel of inflammatory action of long duration, that hardening of the whole or part of a lobe is found ; the vesicular struc ture first suffers, the air vesicles are obliterated, and, often enough, the bronchi and blood vessels of a certain magnitude.
Such portions of lung are dense, not at all friable, possess a peculiar crispness, and con tain little or no air.
The colour of an indurated lung may be light or dark grey, or brown, and rarely pale. A section of a piece of indurated lung shows the circular apertures of the bronchi and larger blood-vessels, surrounded by a dense tissue in which no vesicular structure is seen. The fibrinous dense lymph which produces these changes frequently becomes the nidus for tubercular deposit.
Partial indurations are found around tuber cular cavities and abscesses, and around collec tions of miliary, or of larger tubercular masses.