PATHOLOGY 399 pig- in (1 to
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1 imon i: .m- ii ion. ^ -vous e trol i: aflam c ciou. The same state of the tissues as in phlegmonous erysipelas is brought about, all but the redness of the surface, by a very different cause the introduction of a minute quantity of venom, either the cadaveric venom introduced in a dissection-wound or the venom of the rattlesnake and adder. The bites or stings of many other animals produce more transitory inflammatory effects. In common inflammation, such as follows the lodgment of a spicule of broken glass under the skin of the hand or arm (to bor row Watson s illustration), there is first pain ; soon there is redness around the point of entrance, with swelling and heat ; the skin becomes of a bright-red colour ; the swelling increases, becoming hard and firm at the centre of the inflamed area, and exquisitely tender, or painful to the touch. If these local effects are at all considerable (according to the nature and extent of the injury, and to the sus ceptibility or habit of body of the individual) there is inflammatory fever some hours later. At first there is usually chilliness and feebleness, then there is a general feeling of heat and dryness, with a quick, full, and hard pulse, headache, wandering pains in the limbs, restlessness, some mental confusion, disturbed sleep, a white tongue, thirst, and loss of appetite. If the piece of glass be removed all these symptoms, local and general, may subside quickly. If the source of irritation remain, or even, notwithstanding its removal, if the primary shock has been severe, the symptoms conthme and intensify. Relief to the constitutional disturbance comes with the further developments in the injured area with suppuration or, at the latest, with the bursting or letting out of the matter. Healing then proceeds as described under "repair." This is the usual sequence of events in common inflammation, in the inflammation of moderate degree in a healthy person. It differs from erysipelas or phlegmon in the important respect that the fever follows the local effects at an interval of several hours. Where the injury is of the most violent kind, as in some machinery accidents, neither the local effects nor the fever are pronounced ; the "reaction " is said to be in abeyance, and death is apt to occur from shock. In these cases the face is blanched, the action of the heart and lungs feeble, and the mental faculties profoundly op pressed ; the presiding control has been so upset by the injury to even a limb that the forces of the body do not rally. The heat of an inflamed part is not merely in the feelings of the patient ; it is actually several degrees (up to 6 or 7 Fahr. ) higher than the temperature of the part in health or of the corresponding part on the opposite side, although it is never above the central blood-heat of health. It is not solely dependent, therefore, on the general state of fever. Neither can it be said that the general state of fever is solely dependent on the increased local combustion. In erysipelas, as we have seen, the general fever usually precedes the local, and must depend upon some general error of heat-making. Again, in a common inflamed wouncl, the general fever may, and usually does, subside some time before the cellular changes in the part, degenerative or formative or both, have passed their climax. Implication of the Nervous Control in Inflammation. From slight inflammations, with little more than redness and pain at the seat of injury, to the most shattering strokes there is a succession of steps. The nervous system is implicated in them all, for the reason that the nerves are everywhere, and everywhere ready to transmit impressions to the centre. It is not surprising, then, that in every doctrine of inflammation since the time of Cullen the events have been largely traced to the direct action of the nerves and nerve-centres. Amidst all the conflicting views taken of the nature of inflammation in current writings, there is agree ment on this point at least, that the nervous control has much to do with it, if not always the central control, yet some local control whose existence would hardly be suspected but for the phenomena of inflammation. The differences of opinion begin when we come to the details of the nervous control. Does the nervous system preside over the action of the vessels only, or does it preside over the whole cellular life or the nutrition of the part ? Opinions have had a tendency to range themselves on two sides, corresponding in the main to the more mechanical or to the more "vitalist" conception of life as a whole. The afflux of blood, which every one recognizes as the first conspicuous event in an inflamed part, has been attributed in the latter view to an attraction exercised by the cells of the part, to a hunger for blood comparable to that which causes a determination of blood in an organ that is going to be physiologically active. "The facts," says Alison, " afford a strong presumption that the impressions made on the capillaries, and on the blood contained in them, solicit the flow through them on the principle of a vital attraction of the blood rather than of relaxation of the vessels." This is the "soli citation of fluids," the "movement of turgescence" or the "vital erection of vessels " of the older authors. If the needs of nutrition are the ordinary attraction, they may be simulated by such in cidents as wounds, scalds, and the like ; and it is the peculiarity of inflammation that the incidence of these is on a tissue whose physiological interest is ordinarily of little or no account, namely, the common binding tissue. It is with justice that Rindflcisch emphasizes the intimate connexion between the common binding tissue and the peripheral nerves and nerve-plexuses. " They run exclusively in the connective tissue ; in it they divide and form plexuses, which ultimately join, without any definite demarcation, with the network of connective-tissue corpuscles. Their distribu tion in the connective tissue designates these nerves for some de finite function ; they are admirably adapted to play a part in the general physical and chemical changes of the organs, to give in formation of the same to the central nervous system through their corresponding states of excitation. With the connective tissue they participate in the most intimate structure of organs, with the connective tissue they are stretched and pressed upon, with it also they suffer those chemical excitations which any considerable accu mulation of waste matters brings with it." Now, it is known from numerous experiments that, if a nerve of common sensation be stimulated, the outgoing response from the centre is by way of removing the tonicity of the arteries of the part, so that they dilate and transmit much more blood. This outgoing influence is assumed to travel by a special set of fibres called, for convenience, " depressor fibres," because the effect has been to take off the tonic contraction of the arteries. The same effect is strikingly seen (although it is there accompanied by a conscious mental state) in the rising wattles of a cock, for which class of erectile effects the nerves are called "nervi erigentes." But if this kind of turgescence is the best physiological analogy for the redness of inflammation it goes but a little way with us into the morbid condition. The tonic contraction of the arteries is no doubt taken off, and the vessels become distended with blood passing through them ; but the next event is peculiar to inflamma tion, the current of blood becomes slower, slow even to a stop in some of the numerous cross-channels of the capillaries. There is nothing in the mechanics of the circulation to account for this dallying of the blood at the seat of injury. The further discussion of the subject will be made easier by a reference to slight degrees of inflammation set up experimentally in transparent and delicate parts where the process can be watched through the microscope, in a piece of frog s mesentery drawn out through an aperture of the abdomen, or in the everted membrane -like tongue of the same animal. When the microscope was first applied to the study of inflammation these same effects were often observed by Paget and Wharton Jones in the wing of the bat, an animal which has the advantage of being comparatively warm-blooded. Experimental Study of Inflammation. The frog having been Experi- paralysed by curare, a loop of the intestine is pulled out through a ment in slit in the abdomen, and its mesentery stretched over a ring of intlam- cork, so that the light may be reflected to it from the mirror of the matioii. microscope. It hardly wants an irritant, such as a drop of weak acid, to produce the inflammatory effects on this thin membrane ; mere exposure to the air suffices. In ten or fifteen minutes the arteries begin to dilate and then the veins, and the vessels go on dilating for the next two hours, when they will have reached about twice their ordinary calibre. They remain so dilated, and in an hour or two the current of the blood becomes slower in them. In the older observations on the bat s wing acceleration of the current through the dilated vessels was first noted ; then came the transi tion to the peculiar inflammatory action, namely, slowing of the current, the vessels still remaining dilated. This slowing of the stream is most obvious close to the injured point, where there may be complete stagnation in the capillaries, the croAvded corpuscles giving the central area a brilliant carmine appearance. Farther away from this area the streams are more rapid ; and at the farthest limits there is the unusually full and rapid flow of normal hyper- remia. The fulness of these dilated vessels exhausts their elasticity, so that the pulse-wave of the blood, which should be felt only in larger vessels, becomes perceptible also in the smallest. In the area of retardation in the frog the blood -disks and the white corpuscles cling to the sides of the capillaries and small veins, instead of forming, as usual, a procession in the central line of the tube. Most of all do the colourless corpuscles adhere to the walls, in the experiment on the frog, until they form a kind of outlined mosaic on the side of the vessel. Then, if a particular spot be watched for several hours continuously, it will be found that some of these cells have actually worked their way slowly through the wall of the small vein. This is the important phenomenon of emi gration of the cells of the blood, known to Gendrin and W. Addison, accurately followed by Waller, and rediscovered by Cohnheim. Incontinence of the Vessel-walls. The incontinence of the vascular Incon- walls in inflammation is proved, not only by this emigration oftinence cells from the small veins, but also by the escape of red blood-disks of vessel- from the capillaries, and by the familiar and old-established fact walls, of exudation of the fluid part of the blood, the plasma or serosity. In the words of Alison : "First, the surrounding textures are loaded with a serous fluid ; but gradually changes take place in this fluid, which indicate that other constituents of the blood have exuded from the vessels ; or part of the fluid effused assumes a gelatinous consistence, and forms flakes or layers which gradually become solid. In the semi-fluid matter first effused, according to Gendrin and others, decolorized globules of the blood may often be per-
