extent, but merely in a varicose manner, as here represented; and as red-cells fill the still layer of the capillaries, they seem much larger. The next figure, copied from that in Prof. Bennet's admirable Lectures on MediWeb of Frog's Foot after alcohol has been placed on it.

cine, well illustrates the condition of the capillary circulation in the frog's web under health and disease. To the left, the circulation is normal; in the centre, there is congestion and rupture of a capillary, and hemorrhage has occurred; and to the right, inflammation has been excited by the contact of alcohol, and its characteristic results, stagnation and exudation, have resulted. The black stellate marks are pigment granules. New vessels are not formed in inflammation, but those which were only large enough to admit the plasma may then carry the cells of the blood.

As regards the cause of the appearances we have sketched, or the theory of inflammation, much obscurity prevails. Williams believes the stagnation due to the white cells, which are certainly increased, obstructing the vessels, owing to their adhesiveness. The undoubted muscularity of the capillary walls and the in

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fluence of the vaso-motor nerves, which has of late years been demonstrated, indicate that the process is vital, not mechanical. Virchow states that a muscular contraction of the capillaries first occurs, and is followed by relaxation from exhaustion, as muscular action always is; and, lastly, Simon, in his admirable essay on the System of Surgery," says it is "the result of an increased attraction which the inflaming tissue exerts, as it were, suctionally, on the blood coursing within its capillaries." The inflammatory exudations, which are local results of tissue formation more than products derived from the blood, abound in albuminous matter and in salts, which everywhere seem indispensable where rapid cell-growth is going on. Now, this cell production is most characteristic of inflammation, as plainly illustrated in cartilage, the pathological changes of which, discovered by Prof. Redfern, we have before referred to; and in mucous membrane, which when inflamed generates pus cells, instead of the more permanent epithelial cells. Changes in the blood cannot be regarded as the essential feature of inflammation, for it can scarcely be supposed that that fluid is affected before such local inflammations as conjunctivitis can occur. Alterations do, however, result, and have been alluded to a few pages back, and it may be here added, that its temperature is always heightened, as a result of increased oxidation.

The condition of the system responding to local inflammation, and termed inflammatory fever, mainly depends on or accompanies the hyperfibrinous state of the blood; and in the words of the philosophical writer we have before quoted, "the greater fibriniferousness of the blood in inflammation represents actions of devitalisation and decay in some albuminous material. Whether this changing material be the inflamed texture gradually dissolving itself in the blood, or be the albumen of the fevered blood itself undergoing accelerated waste, cannot,

in the present state of knowledge, be even approximately stated."

The Results of Inflammation are most varied. I. Resolution, to which alone the name of "termination" is applicable. This most favourable occurrence implies the gradual return to the condition of healthy nutrition.— Delitescence, or sudden removal, and metastasis, or translation to a distant part, agree with resolution as far as the part engaged is concerned, for in both it is left in its normal state. II. Effusion of Serum, which mostly follows chronic and asthenic inflammation. Fibrin is present in many effusions, which will remain fluid as long as they are contained within the body; but when withdrawn, especially if a portion of solid fibrin be present, that material rapidly fibrillates. III. Effusion of Blood occasionally oceurs, as in pneumonia, when it colours the sputa; and in chronic cerebritis, when the brain substance is reddened by it. Probably in such cases its colouring matter, and not its cells, is alone present. IV. Exudation, which is the essential feature of inflammation. The material exuded is identical with the plasma of the blood, but in pathology it goes by the name of lymph, of which Paget describes two varieties, fibrinous and corpuscular; the latter being termed croupous by Rokitansky, from the disease in which it is so plentifully effused. Williams classifies fibrin as plastic, cacoplastic, and aplastic.

The difference between fibrinous and corpuscular lymph consists in the greater relative number of whitecells in the latter, and the following circumstances determine the production of one or the other: 1. State of the blood; 2. Seat of the inflammation; 3. Degree of the inflammation. The first point is well shown in Paget's famous experiment: he applied cantharides blisters to thirty patients in St. Bartholomew's Hospital; and on collecting the serum, he found such differences in microscopical and other characters, as to be able to judge of

the disease under which each patient laboured. In sthenic cases, firm fibrinous clots were obtained; in cachetic and phthisical patients, white cells were vastly more abundant, and there were many intermediate degrees. These results explain how various in effect one injury may be to different individuals.

Plastic Lymph is that which is capable of organization; and in order that this event shall take place, all inflammation must cease, and the conditions which we have before stated as necessary for healthy nutrition must be present. The vessels of the tissue on which it lies bud vessels into it. It may develop into fibrous tissue, as it is most apt to do, or may produce fat, elastic tissue, calcareous matter, true bone, &c. The most important property of organized lymph is its wonderful contraction, from which such changes as the following result: deformed chest after pleurisy, cirrhosed liver, spontaneous amputations in utero, narrowed cardiac valves, distortions after burns, and the stricture of mucous canals with which, as surgeons, we have so often to deal.

Cacoplastic Lymph is exemplified in tubercle, so readily examined in the lung. Rokitansky distinguishes the grey and yellow tubercle, but the latter is merely an advanced stage of the former. It at first is laid down in discrete masses, the size of millet seeds (miliary), which project when the lung is cut, as they have less elasticity. The masses then coalesce, and crude tubercle is formed. The colour is like that of cheese, afterwards more yellow and often stained darkly by carbon. The microscope shows a clear blastema, without fibres, granules, and oil particles, chiefly in the yellow and withered and degenerate cells and nuclei. Extraneous matters, such as epithelial and pus cells, fragments of broken down lung tissue, pigmentary and calcareous matter, and cholesterin, are mixed with these constituents. Virchow believes the cells are but those of the epithelium of the air-cells, those in the centre being the oldest and largest by imbibition.

Eventually tubercle may wither and dry up, may calcify, or may soften down into pus, which we will presently discuss as an aplastic product; and this being evacuated, a vomica or irregular abscess cavity results. A few pathologists believe it may be absorbed, and Virchow thinks this may happen after it has undergone the fatty metamorphosis. The softening generally begins in the centre, which is farther removed from the preservative influence of the blood.

Another cacoplastic material may be alluded to-the

false membrane of that fearful malady, diphtheria. It is described by Beale, whose figure is here reproduced, as consisting of a transparent viscid mucus-like material, with wavy lines, entangling epithelial scales, and granular, rounded particles of much smaller size, passing into pus cells in the lower forms of the disease. Acetic acid dissolves the envelope of these cells, as represented in the lower part of the annexed figure, whereas that re-agent makes the cellwall of pus more evident. That pathologist believes "that the greater part of the epithelial layer is stripped off from the subjacent structure in a membranous form; that this is increased in thickness by the rapid development of new cells, having the characters above described, upon the surface of the mucous membrane; and that these new cells, corresponding to the deepest layer of epithelium, lose more and more the epithelial character, and tend gradually to pass into pus corpuscles." Virchow thinks the exudation is into the mucous membrane, which then ulcerates from the tension.