a shut sac; the so-called exudation is therefore found in the one case in the spittoon or the close stool, and in the other within the cavity affected-a slight irritation of the mucous membrane leading to increased secretion of mucus, and of the serous membrane to an increased secretion of serum, a greater irritation of either complicating their natural secretion by a morbid secretion of fibrine; and leading ultimately to the proliferation of the mucous or connective tissue cells as pus in the one case and as fibre cells or pus cells in the other, according to circumstances.

From the days of Hunter the process of ulceration has been referred to an increase of absorption over depositiona purely theoretical idea, incapable of proof, and also inconsistent with many of the facts observed-such, for instance, as the discharge of disintegrated portions of tissue, &c. It has also been referred to the corrosive action of the purulent matter, an action which has been conclusively disproved by steeping bones, &c., for weeks in suppurating cavities, after which it was found they were rather heavier from absorption than lighter from corrosion, and that no softening had taken place except that produced by putrefaction. A more recent view of ulceration is that it is caused by the slow exudation of fibrinous matter, which from the cachectic state of the constitution exhibits an indisposition to active development, and only acts by com pressing the parts, more or less obstructing the circulation through them, and thus causing the gradual death and discharge of the parts affected, differing chiefly from gangrene in being more slow in action, in affecting smaller portions of the frame at once, and in the process being gradually repeated as the ulceration extends. The more modern view is entirely different, and apparently more rational. It may be thus explained:-In the natural state of the skin or mucous membrane, the upper surface we know is continu ally disintegrated and removed by the action of the various external influences. In health these elements are continually renewed by the continuous development of fresh mucus or epithelial cells from the basement membrane. In inflammation, however, it is precisely these young elements, which ought to become thus developed, that are transformed into pus cells, and as the epithelial surface becomes worn away, the collection of purulent matter which has been gradually forming by the rapid subdivision of the young cells, and by the effusion cf serum into the intercellular spaces, gradually reaches the surface, the abscess ripens, and finally bursts; the pathologically metamorphosed juvenile elements are thrown off, and the process gradually extends into the submucous or subcutaneous connective tissue cells, and in this manner ulceration or breach of surface takes place, and this takes place all the more readily the thinner the layer of juvenile element is. In mucous membranes with cylindrical epithelium, therefore, in which this layer is very thin, it takes place much more readily than in those in which the epithelial layers are flatter and denser. In the former class of membranes suppuration hardly ever takes place without breach of surface; in the latter, as in the urethra, copious suppuration often takes place for a long time without any breach of surface. It has not yet been discovered whether the cells of muscle or of other organs are capable of being transformed into pus cells it is not requisite that they should be-and it is almost impossible to ascertain if they can be, because the connective tissue is so inwoven with every organ of the body that its cells are everywhere present. The amount of destruction caused by the apparent solution of the tissue produced by the suppuration, depends upon the amount of fluidity attained by the organic matter surrounding the young elements. When this remains tolerably firm only granulations are developed; that is, those proliferations of the connective tissue cells which increase in size by the subdivision of their nuclei, before

We can readily understand that small fragments of the tissue get broken off, and occasionally washed out with the discharge, and that when the ulceration affects the bones the insoluble calcareous matter

is found mixed with it.

their escape as pus cells, remain visible on the surface of the sore; as the suppuration gradually ceases these contract in size, gradually pulling together the surrounding healthy tissues, and becoming themselves partly developed into simple fibre cells, thus constituting the cicatrization of the sore-a process which was formerly supposed to be due to the renewed effusion of lymph, which became transfused partly into pus and partly into primary cells, becoming fibre ultimately, and thus constituting the cicatrix. Thus we see that the great difference between the modern theories of inflammation and those which, though less recent, can yet not be called ancient, is that while the latter calls in on all occasions the agency of a process termed exudation, and of a morbid material termed lymph or fibrine, which compresses the natural tissues and causes their death and destruction, or itself becomes developed by a generatio equivoca, and under the influence of unknown circumstances, into the pus cells of an abscess, the connective tissue of an adhesion, or the fibres of a cicatrix, the former deduces all their morbid elementary forms of tissue from the juvenile elements of the existing tissues, which under certain morbific influences become metamorphosed into structures, which though far from being identical with their natural physiological form, are yet the pathological equivalents of these forms, developed for certain wise purposes, and in accordance with certain laws, the nature of which is as yet unknown, but which are unquestionably framed for the protection and preservation of the organism, under the peculiar circumstances of its present existence.

The tendency of all modern thought is to assure us of the truth of the latter and more recent view of the inflammatory process, which also receives very important support from the results of enlightened treatment. But into all these matters we must subsequently go more in detail; it is enough for the present to have shown, somewhat cursorily, that inflammation is no morbid novelty, but merely the result of the natural laws of vitality, and of the ordinary growth of tissue, operating under certain anormal conditions.

PUBLIC HEALTH AND SANITARY REFORM,

DELIVERED BEFORE THE DUBLIN STATISTICAL SOCIETY.

By Sir R. J. KANE, M.D., F.R.S.

(Continued from p. 564, Vol. ii., 1866.)

MYSTERIOUS and complicated as are those phenomena, analogous to fermentation, by which it is supposed that certain contagious or zymotic diseases are produced, that process does not suffice to explain all the circumstances under which disease is communicated, and we are obliged to admit that in many, and in some of the gravest instances, morbific influences are propagated through the agency of beings of a higher organization. Science has demonstrated that man and other animals are themselves the material means and pabulum of existence to myriads of beings more or less minute, and of which, in many cases, we can only infer the existence from their lamentable effects. That probably every living organism is itself truly a microscosm, a world in itself, in which infinite series of lesser organisme live and die, carrying in their life or in their death the elements of disease and inevitable decay to the being in which they have been formed. We thus may recognise among the maladies which are known as infectious or contagious the two groups of fermentative and of parasitic diseases; of the former we may regard small-pox as the characteristic type, with probably oriental plague and the cattle disease, from whose ravages this country has so far fortunately escaped. In those the virus may be transferred by inoculation, and acting on materials naturally existing in the blood, generate by a fermentative action, matter of the same kind, which often tends to eliminate itself from the system under various

external forms. Not so easily explained as results of fermentative action are the phenomena presented by the spread of the contagion of Asiatic cholera and typhus fever. Those terrible pestilences appear to inflict their ravages by further means, and many phenomena appear to lead to the belief that those and some similar forms of disease are generated by means of minute beings, which, being diffused through the atmosphere, settle down on certain places, or on certain individuals, in a most irregular and anomalous way, although in all cases favoured by want of cleanliness, drainage, and ventilation, and often directly supplied through water and through communication with diseased persons or places. Such diseases do not admit of being directly reproduced by inoculation, nor can, in most cases, any distinct virus be exhibited; but this is probably due to the imperfection of our means of investigation, and not to any real distinction in the two classes of disease. The transference of such organic germs is illustrated by the curious form of fever which has been epidemic for the last few years in Central Germany, and which has been traced to the development in the muscular tissue of the human body of a microscopic worm, the trichina spiralis, which obtains entrance from diseased meat, especially pork, having been used as food. In this extraor linary disease, every part of the muscular tissue becomes infested with this minute animal, and a small bit of diseased muscle, if inserted in the muscle of a healthy animal, transplants the parasite, which then lives and multiplies in its new position, to the imminent risk of the individual who has afforded it a home. It may interest some of my friends here to know that this little worm, although showing utter indifference to every kind of drug, has an intense dislike to alcohol, and the only individuals in Central Germany who have been latterly able to eat diseased meat with impunity have been those reckless individuals who washed down their roast pork and sausages with copious libations of corn brandy.

From the more definite knowledge of the nature of contagious influences which those observations will serve to indicate, it is apparent that in placing cleanliness, personal and domestic, at the head of the means for preventing or checking the spread of disease, I but carried out the strict principles of science. Every collection of filth, every space occupied by stagnant water or often respired air, becomes a favourable position for the growth and diffusion of those germs of infection. By their being diluted and removed by fresh currents of air, by frequent ablutions, and by drainage, their power to do evil is abated if not destroyed, whilst the freshened energies of life conferred upon the system by the action of those sanative means, enable the organs to resist and to reject those morbific influences to which otherwise they might have succumbed. To those means of resisting disease, however, we need not be necessarily restricted; we may call in the assistance of science in another form, and not merely removing the infectious matter, we may alto. gether destroy and decompose it by means of suitable disinfecting agents.

chlorine is by far the most available, and the most powerful. The direct decomposing action which it exercises on all organic bodies, and the consequent destruction of all vitality in organic germs, such as might propagate disease, renders it the most valuable agent for sanitary purposees that we possess; whilsl the facility with which it can be applied in various forms, as gas, as liquid, and in solid combination, enables it to be adapted to the most varied circumstances. It is only necessary to avoid the liberation in any confined space of such a quantity of chlorine gas as might affect respiration, or produce irritation of the lungs; and this is easily done. Gaseous chlorine when respired has no other injurious effect; it is not in any way poisonous. Many other chemical agents which combine with or decompose organic bodies are also excellent disinfectants, as sulphurous acid, and especially permanganate of potash this body, which is a very powerful oxidizing agent, is now very frequently employed to detect the presence of abnormal quantities of organic matter in air or water. In fact, any substance which is capable of arresting fermentation by destroying the vitality and energy of the organisms which constitute an active ferment, will, for the same reason, arrest and destroy the matter of contagion.

These disinfecting agents, chlorine especially, have the property of destroying foul smells by the same process, of changing the nature of the fœtid material, and generating other bodies which are free from practical inconvenience. They are therefore very usefully employed for the purpose of deodorizing or disinfecting, those words being popularly considered synonymous, the sewage and other similar materials which should otherwise become offensive nuisances. It is, however, very necessary to distinguish between these two actions: an atmosphere apparently pure and bright may be loaded with typhoid emanations; a water clear, fresh-tasting, and sparkling may be infected with the cholera poison derived from drainage through the soil from the neglected sewage of neighbouring infected places. On the other hand, the air of a chemical laboratory, or of a manufactory, may be offensive from the escape of ill-smelling gases or vapours, and yet be totally incapable of producing contagious disease. An atmosphere may, however, be injurious to life from the presence of directly poisonous gases independently of any power of producing contagious disease; and may thus be vitiated by overcrowding, by exhalations from cellars and pits, by the proximity of lime or cement kilns, which diffuse the poisonous gases, carbonic acid, and carbonic oxide. Such air may be rapidly fatal if respired, and yet present no sensible indication of the danger. On the other hand, although sulphide of hydrogen is extremely poisonous when respired, such is the disgusting smell and taste of air containing even one ten-thousandth part of its volume of that gas, that attention is at once called to its presence, and the danger may be avoided. By means of chlorine this poisonous gas is at once destroyed, other compounds being formed which are free from any injurious properties.

Nothing can be considered as really a disinfectant but what can actually destroy the organic germs upon which the propagation of disease depends. Of such bodies

oxidizing re-action in the air is in reality due to the presence of ozone has been latterly more and more called in question. The same re-actions are produced by the presence of minute traces of nitric and nitrous acids. These bodies are continually generated in the air by the unceasing disturbances of electrical equilibrium. The gradual oxidation of organic matter which takes place on the surface of the soil, and in the air itself, also generates those acids, and their quantity in the atmosphere is usually such as to fully explain the re-actions which have been attributed to ozone. I do not myself express an opinion on the subject; I only give the results of chemical inquiry so far as it has yet been carried on. It is, however, certain that the air itself is constantly and powerfully converting the effete organic residues of animal and vegetable life into the materials from which new forms of animals and plants are to be produced, and that thus the neverceasing cycle of vitality ordained by an all-wise Providence is harmoniously carried on-the close of one phase of physical existence supplying the materials from which the substance of the plants and animals of a succeeding generation are to be formed.

This is no merely abstract or speculative principle. The successive utilization of the same material elements in the formation of successive phases of organic life is the basis of practical agriculture; on it rests the whole science of the application of manures. It has the most direct influence on the economy of large cities and on the prosperity of nations; for there is little doubt but that after allowing for the moral and political agencies which contributed to the destruction of the great empires of antiquity from Babylon to Rome, no insignificant element is to be found in the impoverishment of the neighbouring territories, the produce of which was consumed within the great cities without any equivalent being returned to the soil. Hence those lands became finally incapable of supplying food, and the population became dependent on the produce of distant countries, with which a political connection unstable and precarious could not permanently be maintained.

On a smaller scale the same process is going on in modern nations, and indeed with an accelerated pace among ourselves. Every country which is an exporter of food, diminishes by so much its power to produce food. The mineral elements of food, the earthy phosphates of which the bony skeleton is composed exist in the soil, but only to a limited extent, and the supply should soon come to an end if not compensated for by the restoration of as much of the same material under the form of manure. In new countries according as the soil of one district becomes exhausted, the cultivation passes to another, but even in America this can no longer be easily done. With us it is of course impossible, and we must bear in mind that for every ton of bone that we send out of the country we are 80 much poorer in capital, unless we replace it by a ton of bone brought from some other source. Hence the influence of a large city like Dublin is necessarily to impoverish the soil of the surrounding districts, unless means be taken to restore to the soil the residual materials of the food which has served for the support of the inhabitants. The question of sewage, to which I have already referred in connection with the means of health and cleanliness, assumes thus additional importance when considered in relation to restoring the productive powers of the soil. The utilization of town sewage, however, must depend for its practicability on many complex conditions as to form and locality, upon considerations not merely of chemical and engineering skill, but also of financial prudence. Into those matters it would be impossible for me te enter; as regards this city the subject is in the hands of the municipal authorities, assisted by eminent professional opinions, and from what I have seen of the plans recently under consideration, I have no doubt that before very long we shall see our river and its quays restored to their primitive salubrity, whilst what is now a source of defilement and disease, will afford the means of reclaiming new lands to

profitable cultivation, and afford new sources for the sup| ply of food.

I have thus endeavoured to explain in a simple form the general principles of sanitary science, as constituting the third branch of the business of this Society. We have seen that a large class of those diseases which are most destructive, especially to the poor, are in a great degree preventible, by the adoption of simple hygienic means, by cleanliness, by ventilation, and by the use of those disinfecting agents which science teaches us to employ. In the foregoing remarks I have not adverted to that which lies at the basis of all sanitary requirements: the means of providing for the people a proper supply of food. Good and sound nourishment is in itself a powerful sanitary agent, enabling the system to resist tendencies to disease, under which, with a lower standard of living, it would have sunk. So direct is the connection between zymotic disease and want of food that the term famine fever has been adopted in medical classification for that form of epidemic of which in 1847 we had in this country so fearful an example-we must not, however, now enter into that subject. The means for providing the people with good and abundant food is to be found in facilitating the access of the people to industrial employment, and rendering that employment grateful by securing that the worker shall enjoy the product of his toil. In such form, however, the question touches upon matters belonging rather to the practical statesman than to the statistical inquirer, and on which it would be unsuitable for me to dwell. In another aspect, however, the influence of sanitary conditions on the material and financial conditions of the working classes may legitimately be considered here. In no way is the suffering from sickness more severely felt than in the destitution which almost invariably attends the protracted illness of the bread-winner of a family, and the consequent loss of the weekly wages upon which the support of a wife and children usually depends. The inevitable reduction in the amount and quality of food; the absorption of any little fund of savings which the providence of better times had formed; the pledging of the little stock of furniture and clothing; the gradual sinking into destitution, and the loss of energy and hope which throws the family into the conditions most conducive to the still further propagation of disease. It is true that in most of the trades benevolent societies are organized, from which, when properly conducted, great benefits are derived, and much assistance is afforded to their members suffering from sickness; but the sphere of action of such societies is still very limited, and the actual loss of money capital, not to speak of physical suffering and moral depression, consequent upon the spread among the working classes of preventible diseases, presents proportions well calculated to arrest attention when we submit it to inquiry.

My friend Dr. Mapother has very kindly obtained for me some returns illustrating the proportion of time lost through sickness by the working men in various employments in this city. Those estimates, into the details of which I need not enter here, as I hope the subject will be brought fully under the notice of the society at another time, represent the proportion of illness under the circumstances which render it a minimum, as in those employments no absolutely sickly person would be retained. It appears, however, that the average time during which a workman is prevented from earning by illness is from four to twelve days in the year, or as we may take it 2 per cent. of the whole period. Now as there is estimated to be in Dublin of the classes living upon wages 100,000 individuals, we may judge how great, even when taken at its lowest average rate, must be the actual loss in money to the working classes, and consequently to the State, from illness of which, as one-fifth of the total deaths are estimated to result from zymotic diseases, a large part could be avoided by the adoption of sanitary precautions.

But the amount of money measured in this way represents but a very small part of the injury to society, and