or terminating in calcification, which is mineral degeneration.

Perhaps the simplest example of caseation or fatty disintegration of fibrin is that occurring in the centre of clots of fibrin within vessels, the true nature of which was first pointed out by Mr. Gulliver. The appearance of

failed, and intestinal irritation and hectic fever increased. Cod-liver oil was then tried, and agreed, but with no good results; and after repeatedly passing by the bowels sudden discharges of fœtid matter, with blood and mucus, the patient died (July 12), in extreme emaciation.

On examination thirty-six hours after death, the abdomen was found distended, chiefly by gas in intestines. Very little fluid in peritoneum, and no lymph or tubercle. Right lung closely adherent to anterior and upper wall of the chest, its tissue compressed and congested, with patches of yellow tubercle; and the whole lower lobe, and a large part of the upper, converted into a caseous mass, with layers of the same opaque curdy matter on the pleura covering the caseated portions. Few traces of the lung tissue could be distinguished in the most opaque cheesy parts; but bronchi were found abruptly terminating in it in irregular excavations, comparatively dry, and without any membrane or vessel, and only here and there could a tinge of blood be seen. Deposit, tissue, and all, seemed degenerated into a mass of opaque, yellow, friable, tuberculous matter. Similar caseous matter was found in the bronchial glands, and spread under the costal pleura, and even under the peritoneum lining the lower ribs. Left lung generally crepitant, and free from adhesions, except near the root, where were several small yellow and friable tubercles, and a small patch of opaque yellow lymph on the pleura over one of these tubercles. Heart small and flabby. Bronchi pale and dry. Liver lay low in abdomen, being somewhat enlarged, and also depressed by the caseous deposit in right lung and pleura; it was closely adherent to diaphragm. Tissue rather tough; red, not mottled. Nothing remarkable in other organs.

This case presents a clear example of what has lately been regarded as scrofulous pneumonia. At the time I considered it a striking instance of caseous degeneration of the products of inflammation both in the lung and on the pleura. The fatty transformation and disintegration of both products and containing tissue here superseded all vascular action or irritation; so that consumption did its destructive work almost without pain, cough, or expectoration.

1 Med.-Chir. Trans. vol. xxii., 1839. I promptly availed myself of this discovery in showing that this softened fibrin in aspect and microscopic composition differs in no essential particulars from those of softened tubercle.' (Princ. of Med., 1843, p. 324.) The subsequent observations of Virchow on the same subject have not given due credit to Mr. Gulliver's discovery.

DISINTEGRATION OF FIBRIN.

49

spots of opaque softening in the emboli of veins had been previously mistaken for pus; but Mr. Gulliver found under the microscope that they contained no pus globules, but merely broken-down fragments of fibrin, with an abundance of oil globules, the formation of which caused the disintegration.

Instances of a similar change may be seen in fibrinous vegetations on the valves of the heart, and in the shreddy lymph covering the pericardium and pleura, when prolonged inflammation of these membranes reduces their products from plastic to aplastic. In fact, in some cases, called empyema, the fluid effusion is not truly purulent, but consists of serum, holding in suspension numerous minute flakes of opaque degenerated fibrin, whilst large shreds of the same material still adhere to the pleura or pericardium. In true empyema there is little or no coagulable lymph, or curdy matter. All the plasma is converted into pus globules and liquor puris; and this transformation of the sarcophytes, the suppurative, demands a brief notice in this place, as contrasting with their more degraded condition in tubercle. This we will consider in the next chapter.1

The decided tendency thus shown in tubercle to spontaneous change renders the results of ultimate analysis of its composition uncertain. I am not acquainted with any accurate analysis having been made since that of Scherer, which is as follows:

'Crude pulmonary tubercle yielded little fat or extractive matter. An ultimate analysis, after the most careful removal of foreign constituents, gave:

6

Hence tubercle may be regarded as protein (C48 H36 Ne 014), from which five atoms of carbon, one of hydrogen, and one of oxygen have been removed.'-Simon's Animal Chemistry, by Dr. Day, vol. ii., p. 479.

E

CHAPTER VII.

ON THE NATURE OF PUS AND SUPPURATION.

Pus cells modified Sarcophytes; partly liquefied by oxidation-Circumstances favouring it-Result aplastic and destructive, but with salutary intent-Favourable issues—Termination of abscess in Caseation and Petrifaction Gradations of lymph, pus, and tubercle.

6

ACCORDING to several observers (Beale, Von Recklinghausen, and others), pus globules exhibit the living properties of germinal matter, or active bioplasm, in their spontaneous motions, in their rapid proliferation, and in their power of absorbing and assimilating other matters. But we cannot understand fully the process of suppuration without due consideration of the chemistry of the process, which has a chief share in determining the liquid condition and disintegrating properties of pus. The chemical change which accompanies and probably causes this disintegration and liquefaction in the formation of pus seems, according to the researches of Mulder, to be an increased oxidation of the protein, whereby it passes from the state of a solid deutoxide into that of a tritoxide, which is readily soluble in water or serum. But this further oxidation and solution implies also' a frustration of the vitality of the exuded corpuscles, which, although still moving and multiplying, 'lose their organising power, and degenerate into a diffluent aplastic material. Probably, in some instances, the corpuscles' (sarcophytes) are originally defective in organising power, and are, therefore,

1 Simon's Animal Chemistry, by Day, vol. i., p. 12.

NATURE OF SUPPURATION.

51

prone to degenerate; whilst in others they become so from depraved nutrition or other circumstance spoiling their plastic power.

"The circumstances which determine suppuration as a result of inflammation are chiefly three:-(1) A certain intensity and duration of the inflammation; (2) the access of air to the part; (3) a peculiar condition of the blood. 1. Intensity and continuance of inflammation comprise the persistence of the two chief elements in the process, determination of blood and obstruction; and as we have seen that the physico-chemical effect of these is first to direct the force, and to exaggerate the influence of the red corpuscles (which convey oxygen) on the liquor sanguinis, so that more of its protein passes into the state of solid deutoxide '-the material of sarcophytes- fitted for organisation and reparation, so we may infer that the excessive degree or continuance of the same action may overdo the change, give chemical properties an ascendency over the vital powers, and, by turning the most recently formed solid into a fluid tritoxide, it may effect a work of segregation and destruction, involving the blood in the obstructed vessels, and extending to the albuminous matter of the containing texture. Such a result is most likely to ensue in complex and highly vascular structures, in which the effused matter is retained in intimate contact with the blood-vessels; hence intensity and continuance of inflammation in the true skin, connective tissues, glands, and most parenchymatous organs, pretty surely lead to suppuration. In serous and fibrous membranes, on the other hand, suppuration is a rarer result, because the vessels are few, and the effused corpuscles (sarcophytes) placed less within their influence.'- Principles of Medicine,' 3rd ed., p. 364.

Referring to the above work for the further explanation and substantiation of this view, I would now add that

mature reflection and modern research have not shaken my belief in its correctness. Recent observations have given a clearer insight into the vital properties of the plasma and its representative sarcophytes, and have supplied more definite facts in the process of histogenesis; but the chemistry of the inflammatory process has not made similar advances, and has been too little considered by the most modern writers. It is a subject that requires further experimental investigation; but in the meantime I propose this view as consistent with our present knowledge concerning the chief varieties of abnormal nutrition.

The rapid increase of the germinal matter or sarcophytes in inflammation is the result of that combination of increased flow of blood to the part, with obstruction to its passage through it, which characterises inflammation. The sarcophytes, thus supplied with abundance of pabulum, increase and multiply rapidly; and under the exeiting influence of the oxygenating arterial currents, and of the heat evolved by it, this multiplying germinal matter displays all its lively properties of motion and migration, through the coats of the obstructed vessels, into the surrounding textures, where it exerts its digestive and assimilative powers, which are communicated also to the germinal matter already existing in the cells of the connective and other tissues; and if the inflammatory orgasm (determination of blood, with obstruction) continues, the multiplying, digesting, and oxidating process goes on until the whole mass is converted into pus, in which the sarcophytes have become loose cells, with liquid tritoxide of protein within and without. Such is the result in complete suppuration, or abscess; in which the somatic life and integrity of the part is sacrificed to the molecular life and chemical action, ending in destruction of the tissues.

This process of suppuration, although thus destructive to the part, and often producing other mischievous results,