Together with the unequivocal evidence of inflammation in other parts of the heart, the muscular fibres have at the same time been found very soft and loose, and easily torn; and with this looseness of texture the heart has sometimes presented a dark and almost black appearance, and sometimes it has been almost blanched and colourless. The deep dark tinge shews that the muscular substance is unnaturally loaded with blood; whereas the absence of colour shews that it is destitute of its natural quantity. These different appearances do, in fact, belong to different stages of the same disease. The first indicates inflammation of the muscular substance in its present state of activity; the second, an irreparable disorganization of the muscular substance left by inflammation, when it has been unarrested in its earliest stages. The first is found when death takes place _in a few days after_ the accession of the disease; the second, when the patient survives the first attack, and dies at a remoter period. The inflammation, which produces softening and attenuation of the muscular structure, is, I believe, always of an acute kind. But induration and thickening of the muscular substance of the heart is also the result of inflammation. This must be distinguished from hypertrophy, or mere augmentation of bulk, of which we shall speak hereafter. In this induration, which proceeds from inflammation, there is, besides increase of bulk and firmness, a manifest alteration of texture. A substance[13] is produced offering a peculiar resistance to the knife. This condition unquestionably must result from an interstitial deposition of new matter among the muscular fibres. From concomitant circumstances, as well as from its own character, I presume that it proceeds from chronic, not from acute inflammation. I confess that I never saw a specimen of what I now allude to. It is described with some minuteness by Corvisart; but it may be presumed to be very rare, since Laënnec admits that it never fell under his observation. These opposite states of softening and attenuation in one case, and induration and thickening in another, are known to those conversant with morbid dissection as the evidences of inflammation in other parts of the body besides the muscular substance of the heart.