Some modifications of this third form of affection of the skin may be met with occasionally in the course of the disease. Blotches assuming a livid or dusky red appearance (which gradually fades into the colour of the surrounding skin), will present themselves in different parts (Case XXXVI), and terminate in thick exfoliation of the cuticle, or in small sloughs of the skin. In some instances, the superficial portions only of the skin are destroyed, and the parts beneath appear comparatively unaffected; small circumscribed portions of the outer layer of the skin will exfoliate, and the subjacent parts will heal without suppuration, by a process similar to that of scabbing (Case III).
It is remarkable in this disease, that the most vascular parts are those which soonest lose their vitality. Thus, in the case last referred to, portions of the surface of the skin perished, while the deeper layers recovered; again, it is not unusual to observe the whole thickness of the skin destroyed, without any corresponding affection of the cellular membrane beneath. The quantity of blood sent to a part would thus appear to favour mortification in this disease. The reason of this peculiarity will be considered in the next section.
In two of the instances recorded in the Appendix (Cases XXII and XXVI), the lining membrane of the rectum was found of a very dark colour, and in one it had assumed a greenish appearance. This discoloration was at first looked upon as some accidental complication, or as depending upon previous disease. But M. Gaspard has noticed a similar condition, after the artificial introduction of putrid fluid into the blood.[34] In one of the experiments referred to, the mucous membrane of the intestines was everywhere healthy, except in the _rectum_ and _duodenum_. In the former situation, the rugæ were prominent, and of a violet colour; in the latter, the membrane was of the colour of pale lees of wine. From the coincidence thus observed, we are led to believe that the same condition which produces congestion in the skin, may produce an analogous affection of the mucous membrane. Nor must we omit to note, in connexion with this subject, the fact of the mucous membrane of the vagina being occasionally found of a dark purple colour in those who die of puerperal affections.