affording a kind of scale whereby to apportion the activity of treatment; to the chronic affection we must oppose a remedy of slow and gradual action the acute must be met more "heroically." It is important to be aware that an inflammation may be sub-acute or chronic from the outset; an acute inflammation cannot well be overlooked-a chronic, if unpreceded by acute symptoms, may easily be: such inflammations are sometimes said to be latent. Congestive inflammation differs not much from asthenic; its effusions are of the same kind, but it partakes in a considerable degree of the nature of passive hyperæmia— indeed, is such originally, and has, subsequently, inflammation, acute or sub-acute, grafted upon it. This must be remembered in treating it. The chief character of erythematic or erysipelatous inflammation is its tendency to spread and travel over an extensive surface: this seems to depend, at least in part, on the peculiar character of the effusion, which consists, for the most part, of serum, or sero-purulent matter, and not of fibrin, which in phlegmonous inflammations establishes a barrier between them and the surrounding textures. The general symptoms are in most cases those of adynamic or typhoid fever; depletion is injurious, and stimulants required at an early period. There is good evidence to show that a peculiar poison, capable of being communicated by infection, is the cause of these inflammations, and that this acts upon and modifies the system, even before the phlogistic process has made its appearance. They are, therefore, with respect to their exciting cause, to be ranked together with other inflammations, such as the rheumatic, gouty, syphilitic, &c., which each manifest certain peculiarities, but depend, essentially, upon the presence of some materies morbi in the blood. To the same class belong most of the inflammations which constitute skin diseases, which exhibit very remarkable instances of the effect of different states of the blood in determining the kind of inflammation that shall occur. To this we shall refer again, under the head of "Crasis." These inflammations also exhibit very clearly the affinity of certain parts of the tissues for certain morbid matters, which are their exciting causes; thus, lepra has its seat of election about the prominence of the knees and elbows, eczema prefers the side of flexion of the limbs and the bends of joints, lichen affects the outer sides. The same is exemplified in the action of many medicines and poisons; arsenic, in small doses, produces conjunctivitis-in larger, inflammation of the stomach and intestines, corrosive sublimate inflames the larger intestines, mercury, the gums, and so on: in all these cases the affinity or attraction of the elements of the tissue for the substance is clearly evinced. Diphtheritic inflammation is characterized by the early exudation upon mucous surfaces of a film or membrane of fibrinous matter of dirty white or grayish appearance; this may extend over a considerable tract, commencing often in the fauces, and thence spreading to the mouth, the larynx, the air-passages, the oesophagus, and more or less of the alimentary canal. The subjacent mucous membrane is but little swollen, of a deep dull red, and inclined to bleed on the removal of the exudation. The attendant fever is of a low kind, and much of the danger depends upon the insidious, almost latent manner, in which the exudation takes place, so that suffocation may be actually threat

ened before alarm is taken. This kind of inflammation occurs most often in epidemics, and is more frequent on the Continent than in England. It has been observed in France, that, during its prevalence, wounds and ulcerations assumed an unhealthy character, and were indisposed to heal. Its cause is, evidently, a peculiar asthenic state of the system generally, involving a peculiar crasis of the blood, induced by atmospheric influences. Instances of a somewhat similar kind, but in which the asthenic character is much less marked, are occasionally met with among ourselves; among these we should rank the so-called bronchial polypi, the pieces of membrane which are passed after the irritation of calomel, and in some other cases of intestinal disorder, and, probably some of the membranous exudations of dysmenorrhoea. The aphthæ of children and adults belong more to the true diphtheritic exudations; they contain, often, a large proportion of a confervoid growth, which has been regarded, indeed, as constituting their essential cause. This, however, in Rokitansky's opinion, is not the case. To this subject we shall refer again, under the head of "Parasites." Hemorrhagic inflammation is another variety; it seems chiefly to occur in individuals predisposed to hemorrhage, or in places where scurvy is prevalent. Dr. Williams has found it associated with cirrhosis of the liver, and granular degeneration of the kidney. His opinion is, no doubt, correct, that it is more dependent on an altered condition of the coloring matter, than on a deficiency of the fibrin. Its character is decidedly asthenic. Scrofulous inflammation is not so much a distinct variety as some others. It is commonly excited by the irritation of existing tuberculous deposit, which is occasionally mingled with its exudative products. These are distinguished in general by their aplastic character; they are deficient in coagulating fibrin, and are often thin and serous. The vital power of the system, both blood and tissues, is essentially defective; and is the cause, at once, of the deposit which excites the inflammation, and of the low character of the process itself.

We have already alluded to the causes of inflammation in the foregoing remarks, and shall now do little more than briefly enumerate them. Predisposing causes are almost always debilitating influences; a strong part is less liable to inflame than a weak one-a previous attack of inflammation especially renders a part more prone to undergo a second. Certain unhealthy conditions of the blood (of which that induced by foul air is one) predispose the system to inflammation from trifling causes, which would pass inoperative in a sound state. Exciting causes are either such as act on the part directly which they inflame, or indirectly through the medium of another. The first may be mechanical irritants, such as a splinter in the flesh; or chemical, as a strong acid, or acrid salt; or vital, such as mustard, &c., whose operation only affects living structures. It is remarkable that the urinary and biliary secretions which excite only healthy action in the mucous surface over which they naturally flow, and which, or at least some of their constituents, produce no particular injurious effects when absorbed into the blood, act as the most violent and fatal irritants upon serous membranes, and the areolar tissue, when infused into them. This shows

clearly the important part played by the tissues themselves in the process of inflammation: that which is a healthy stimulant to one texture is the cause of destructive inflammation to another. The production of local inflammations from the presence of some substance in the general mass of blood, for which certain parts seem to have a special affinity, has already been noticed, but we may add, that it is in these cases that we observe the interesting phenomena of symmetrical disease;1 the corresponding parts of the two lateral halves of the body being affected almost to the exclusion of others. Here, again, we have evidence of the predominant influence of the tissues, the parts which are exactly alike are affected alike, and the materies morbi passes by others. How unable is the neuro-pathological theory to explain such instances of inflammation!

The second class of causes are those which act indirectly on the part which suffers. The most common of these is cold, which appears to act by repelling the blood from the surface, and causing it to accumulate in some internal part. This will be different, according to the previous predisposition; thus one person, as the result of a severe chill, will have bronchitis, another diarrhoea, a third peritonitis, a fourth renal congestion, and so on. Malaria, the repelling of eruptions, the arrest of habitual discharges, the sudden healing of ulcers, are also recognized as causes of internal inflammations, which they probably produce in the same way as cold, but the active congestion of the incipient process is more apt to issue in hemorrhage. It is matter of much uncertainty as to how many inflammations originate; they come on, as it seems, spontaneously, without the individual being aware of any exciting cause. Both as respects these, and those which are produced by cold, &c., it seems to us necessary to recognize some special condition of the tissue, which in the one case converts the congestion into an inflammation, and in the other, is the sole and efficient cause. In ague, for instance, during the cold stage of each paroxysm, considerable congestion of the internal viscera takes place, but inflammation of these is comparatively rare. In healthy states of the system, the surface may remain severely chilled for several hours, during which the blood must accumulate in the internal organs, but this does not occasion inflammation. These instances show that mere repellent influences producing congestion are not adequate to produce inflammation solely by themselves. Even in the case of a common catarrh there is much reason to believe that the inflamination of the mucous surface depends much more on some preexisting dyspepsia, or unhealthy condition of the blood, than on exposure to cold or wet; and, in fact, many a cold occurs without any such exposure. In such cases, the predisposing cause becomes the most important, or may even be the exciting also. We have not yet noticed the nervous influence in its relation to the causes of inflammation. This is considered the prime mover in the process by those who adopt the neuropathological theory: in our view it holds a very secondary place. That disturbance of the nervous force may prove a cause of inflammation,

For a most interesting exposition of the subject of symmetrical diseases, we refer to Mr. Paget's Lectures for 1847.

cannot be doubted: Lallemand (quoted by Dr. Williams) "relates a case in which a ligature, involving the right brachial plexus, was followed by inflammation and suppuration of the opposite hemisphere of the brain. Mr. Paget mentions a case in which a portion of a calculus impacted in the urethra excited inflammation, with deposits of lymph and pus in the testicle. Instances of a similar kind, or of active hyperæmia similarly occasioned, are not very rare, and they certainly prove the capability of the nervous influence to set on foot the inflammatory process. But we have already given abundance of evidence that it is not through this channel that the causes of inflammation usually operate, and for a summary of the arguments we would refer to Dr. Williams's work, p. 249. Coinciding, as we completely do, with Mr. Paget, in his enumeration of four conditions as necessary to healthy nutrition, and believing that the derangement of one of these primarily, with secondary derangement of the others, occurs in every case of inflammation, we might divide the various causes which we have noticed into such as affect (1) the contractility of the vessels; (2) the healthy crasis of the blood; (3) the nervous influence; (4) the life and nutritive actions of the part.

In strict language, there is only one termination to the inflammatory process, viz: that which is commonly called resolution, in which the diseased action ceases to advance, and then recedes by the same steps as those by which it arrived at the condition of stasis. The microscopically visible phenomena have been before described, and they correspond to the subsidence of the general symptom, to the paling of the redness, the lowering of the temperature, the lessening of the swelling and pain. The recovery of the part may be complete; but more often some, it may be slight, indications remain, for a time, of the by-past malady, and of some deficiency of the vital powers. These consist, in some degree, of congestion of the vessels, especially the veins, from an enfeebled state of their contractility, in a less perfect fulfilment of the function of the part, and in a proneness to relapse on the application of slight exciting causes. Inflammations which arise in consequence of a mal-crasis of the blood, rarely undergo resolution, or if they do, it is only to reappear in another part, and perhaps a more important. This constitutes metastasis. A good example of this transfer of inflammation from one part to another is afforded by some cases of rheumatism, and occasionally by the disease called mumps. As long as the materies morbi continues to circulate in the blood, it will tend to excite inflammation in one part or other; the best thing that can happen is, that it should locate itself in a part where it can produce no serious effects from interference with important functions, and there remain until the dyscrasia is at an end. One important remark of Rokitansky's must not be omitted, viz: that even resolution does not, especially if the inflammation has been extensive, leave the system in as favorable a condition as before the attack, since a large quantity of liquor sanguinis, which, during the stasis, has undergone certain changes, is set free, to mingle with the general mass of the blood. This must produce a contaminating effect until it be eliminated. Hence the benefit of a free action of the skin, of a free flow of urine, purging, &c.

But in order that resolution may take place, it is absolutely essential that no considerable amount of effusion should have occurred; if this is the case, the affected tissue remains clogged and otherwise injured by the presence of solidified matter in its interstices. This matter and the tissue may also undergo further changes. We thus come to the consideration of, firstly, inflammatory exudations; and, secondly, of the changes that take place in the tissues affected by them. The fluid effused in inflammation is commonly the liquor sanguinis, more or less modified, especially containing a less proportion of albumen and fibrin. An analysis, by Simon, of fluid obtained by paracentesis thoracis, shows, in 1000 parts, 934.72 of water, 1.02 of fibrin, 1.05 of fat, 48.86 of albumen and albuminate of soda, 11.99 of extractive matter, and 9.5 of fixed salts. The quantity of fibrin varies considerably. Some effusions consist chiefly of it, others contain very little; generally, it may be said, its quantity is in proportion to the vigor of the system, and the acuteness and sthenic character of the inflammation. The fibrin may coagulate quickly, or remain in its fluid state, for a length of time, in the part where it is effused. Blood-corpuscles, or dissolved hæmatin, may be mingled with the exuded matter in various proportions. Though we often speak of serous effusions as the result of inflammations, yet the opinion expressed by Mr. Paget is probably correct, that "an effusion of serum alone is a rare effect of inflammation, and that generally it is characteristic of only the lowest degrees of the disease." He mentions as instances inflammatory oedema of the mucous folds above the glottis, chemosis of the conjunctiva, and some forms of hydrocephalus. The fluid obtained from blisters contains either distinct fibrinous coagula, or only a small proportion of fibrin, together with multitudes of puriform corpuscles.

No doubt, in inflammations of different characters, there must exist great differences in the composition of the serous fluid effused, and in its particular qualities and tendencies. There must be great variations

bands.

in the proportion of oil, of extractive and saline matters in the effusions; but respecting these we have scarce any information. The chemical examination of inflammatory products is very difficult, partly in con