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.
In the cellular membrane, serum, lymph, and pus, may be deposited, mixed with each other in various proportions. The surrounding vascularity, in these cases, is unusually small, and the lymph effused not properly organized; there is, consequently, no natural boundary to the disorganizing process, and the fluid secreted becomes infiltrated in the surrounding parts.
When the muscular structure is affected, suppuration takes place with great rapidity; portions of muscles may be found quite soft, and sometimes pultaceous, in circumscribed patches, around which the fibre is perfectly healthy. Pus is occasionally deposited on the exterior of muscles; and it will be then smeared over the surface, and rather infiltrated in the cellular tissue, than contained in a cyst. In the interior of muscles, there is the same absence of the natural limit to the inflammation; but, owing to the more compact structure of the part, the deposits of matter generally remain circumscribed.
The brain and its membranes frequently present diseased appearances in those who die from secondary inflammation; these, for the most part, may be altogether independent of any peculiar effects of the disease; but, in some cases, it appears probable that they are not altogether unconnected with it. In one of the accompanying cases, the pons Varolii and medulla oblongata were found of a pink colour, in consequence of congestion, where the system had become contaminated by the absorption of diseased secretion; and, in another, a layer of purulent lymph was found within the cavity of the arachnoid, accompanied by marks of inflammatory action in the fourth, and in one of the lateral ventricles.
The serous membranes are peculiarly liable to be attacked by secondary inflammation; and, when affected, suppurate with the greatest readiness. They generally exhibit but a slight degree of vascularity, and sometimes scarcely appear more injected than in their natural condition. In the peritoneal cavity, large quantities of unorganised lymph are frequently poured out, mixed with turbid serum or pus. The synovial membranes of joints, when affected, appear to run directly into suppuration, and will become distended with pus in a very short space of time. The pleura, on the other hand, will seldom suppurate at first; but lymph will be deposited upon its surface, and its cavity will contain turbid serum, occasionally mixed with blood.
XI. In the first sections, the changes produced in the blood, both in and out of the body, by the admixture of purulent or diseased secretions, were considered; and, in the last section, the post-mortem appearances observed in the different organs of those who have died in consequence of secondary inflammations, have been described. It now remains to connect these two series of observations, and to trace the relation that they bear to each other.
The most direct way in which diseased blood produces disease in the parts to which it is conveyed, is by communicating to them its own condition. Even foreign substances, which have no natural connexion with the body, may, in this way, be conveyed in the blood, and deposited in the organs of the body. Hunter relates a case,[35] in which a house-painter, who had been paralytic in his hands and legs for a considerable time, had his thigh broken, and died, about three weeks after, of the accident: "On examining the body, after death, the muscles, particularly those of the arms, had lost their natural colour; but, instead of being ligamentous and semitransparent, as happens in common paralysis, they were opaque, resembling exactly in appearance parts steeped in a solution of Goulard's extract. From this case it appears, that the lead had been evidently carried along with the blood into the muscles themselves. The blood can thus receive and retain extraneous matter capable of destroying the solids."
If foreign matter may, in this way, be conveyed to different parts of the frame, and there produce its chemical effects, it will readily be admitted, that a mechanical or vital action commenced in the blood,[36] may be continued in it when moved to a different part of the body.
In those who die of secondary inflammations, the result of such actions may frequently be traced from the seat of the primary injury even to the heart itself; and, as it has already been shown that contaminated blood will communicate morbid action to the vessels in which it is contained (section iii), there no longer remains any difficulty in accounting for the sudden way in which this disease may fall upon a particular organ, or the unexpected manner in which the symptoms may shift from one part of the body to another. The conditions of the blood, which may be observed upon dissection, in this disease, so far as they tend to illustrate the present subject, may be included in two general expressions: 1st, those in which the blood has had a preternatural tendency to coagulate impressed upon it; and, 2nd, those in which its coagulating power has, to a greater or less extent, been impaired. In one case, the blood is generally found of a dark colour, with firm, and sometimes adherent coagula in the vessels; in the other, it is thin and fluid.
When a preternatural tendency to coagulate has been impressed upon the blood, it will lodge in different parts of the vascular system, in situations which are most favourable to such an action; when, on the contrary, it has lost its coagulating power, extensive effusions may be expected, or the symptoms included under the term "gangrenous diathesis" may manifest themselves.