TUBERCULAR LEPROSY.—This form may declare itself at once by the characteristic tubercles, but frequently an earlier manifestation is the appearance of macules or dull red spots, varying in size from a pea to two or three inches in diameter. They have an indistinct margin, a glazed and smooth surface, and become paler on pressure. The patches, although not at all or but slightly elevated above the general surface, are firmer, and penetrate more or less deeply into the cutaneous tissues. They may increase in size peripherally and undergo involution in the older central portions simultaneously. During the latter process the color changes from a more or less dull red to a brown, yellow, or grayish tint, and finally may become quite white. The spots also become thinner or even slightly depressed. Their seat is principally the trunk, but also the limbs, and less frequently the face. This condition of the skin may precede any other changes in its tissues for months or years, the patches appearing and disappearing or remaining as permanent stains. At last well-defined tubercular elevations show themselves, varying in size from a small shot to a filbert, flattened or semi-globular in form, generally smooth and firm to the touch, and of a dull red or brown color. They occur upon any part of the surface, but are especially abundant upon the face, where they may cause great deformity of the features. The forehead and eyebrows may become very greatly thickened by general infiltration, or thrown out into very prominent folds and protuberances by the massing of individual tubercles. The lips thicken, the nose broadens, and the ears stand out conspicuously with their increased bulk. All these changes in form, with the great darkening in tint which is often present, give at times a most repulsive expression to the face. The tubercles are sometimes to be felt imbedded in the skin, or considerable areas are found to be uniformly thickened and scarcely at all prominent. All forms are capable of involution after an existence of months, and may leave dark-colored atrophic patches to mark their seat. They are rarely painful, and occasionally slightly sensitive. They may be transformed into ulcers, especially upon prominent positions, as the knuckles, elbows, knees, as the result of pressure or injury, which are extremely indolent, although shallow, and may heal and break down repeatedly. Occasionally they give rise to serious complications—inflammation of the lymph-vessels, suppuration of the joints with loss of the attendant members, as the fingers and toes. Tubercles appear also upon the mucous membrane of the nasal cavities, the mouth, and larynx, often in great abundance, causing a very characteristic hoarseness or loss of voice. With these changes in the cutaneous tissues, which may be accompanied in their periods of greatest activity by febrile disturbances, there are developed after months or years, with gradual failure of strength, manifestations of changes in the internal organs, the lungs, intestines, and brain, which may prove fatal at any time, or the patient may die of slowly progressive marasmus. The course of the tubercular form is on the average between eight and ten years. At any period there may supervene manifestations of the anæsthetic type, which makes the so-called mixed variety, in which either form may predominate.

ANÆSTHETIC LEPROSY.—This variety is characterized by the loss of sensation in the skin over areas of varying extent, which occupy no definite positions in relation to nerve-distribution. The anæsthetic patches may appear upon the seat of old maculæ or former tubercles or of a preceding bullous efflorescence, or upon parts not previously affected in any way. They may follow a reddened and hyperæsthetic condition of the cutaneous tissues, or they may be surrounded by a serpiginous border of this character. The degree of anæsthesia in the affected parts is sometimes so complete that the skin and underlying tissues may be deeply pricked or cut or burned without the patient being aware of the injury. Such patches may possibly regain their sensibility. Their surface appears in later stages dry, wrinkled, shrunken, and of a brownish color, and atrophy, not only of the skin but of the muscles, is gradually developed, in consequence of which the expression of the face undergoes a marked change. The eyelids and lips droop, the hair falls, the hands contract, and the joints of the fingers and toes are laid bare, so that the phalanges, or even the whole hands and feet, drop off. Ulceration or gangrene of the parts may develop, and whole extremities may shrivel up. With these manifestations of local derangements of nerve-action the functions of the brain fail, the patient becoming stupid and incapable of action or motion, the temperature and pulse are lowered, and death comes slowly by marasmus or the most various complications—tetanus, disease of the lungs, pyæmia, etc. The average duration of this form is from eighteen to twenty years.

PATHOLOGICAL ANATOMY.—The structural changes which take place in the tissues of parts which are the seat of the appearances above described have received the special study of many excellent observers9 in recent times, and are now well understood. A section through the thickened skin or a tubercle shows the corium and underlying connective tissue infiltrated with round cells, as in lupus and syphilis; in other words, converted into "granulation tissue." This change first takes place along the course of the cutaneous vessels and glands, penetrating more deeply and forming a firmer cell new-growth in proportion to duration, the cells being enclosed in a coarse meshwork of fibrous tissue, and encroaching upon the various structures of the skin, so as to produce atrophy and finally destruction of all its characteristic tissues. This cell-infiltration may of itself undergo later changes, as fatty degeneration and softening (ulceration). The lymph-glands and corpuscles assume a special fatty metamorphosis. An examination of the tubercles upon the mucous membrane reveals the same small-celled new-growth. In the nerve-tissues also marked structural changes are found, both in the central and peripheral systems, in the anæsthetic form of the disease. In many cases the posterior segments of the gray cornua and the fibres of the commissure, as well as the nerves of the extremities, have been found altered by inflammation, which will account for the disordered sensibility and the subsequent disturbances of nutrition, muscular atrophy, etc. The nerve-trunks are often to be felt beneath the skin, thickened and sensitive on pressure. The chronic cell-infiltration affects the fibrous structure of the outer sheath, the neurilemma, and the septa between the nerve-bundles, producing fatty metamorphosis and atrophy of the nerve-bundles. Similar cell-infiltrations are found also in the connective tissue of all the internal organs of the body, which lead to destructive processes in their respective structures.

9 Boeck and Danielssen, Traité de la Spedalskhed, Paris, 1848; Virchow, Die Krankhaften Geschwülste; Kaposi in Hebra's Lehrbuch der Hautkrankheiten; Monasterski, Vierteljahressch. für Derm. u. Syph., 1879, p. 203; Hansen, Virchow's Archiv, Band 79, 1880; Neisser, Virchow's Archiv, Band 84, 1881; Cornil et Souchard, Annales de Derm. et de Syph., 1881, No. 4.

Within the last two years repeated observations have been made which confirm the statement published by Hansen in 1873, that a peculiar bacterium occurs in leprous tissues, which, it is claimed, establishes the parasitic nature of the affection. These examinations have been carried on with leprous material derived from many parts of the world, and the results have been uniform. Within the round cells which characterize the cutaneous neoplasms, both in the distinct tubercles and the diffused infiltrations, small agglomerations of minute rod- or staff-like bodies (bacilli) are found, arranged in parallel rows or placed end to end. Their length is one-half or three-fourths the diameter of a red blood-globule, and their breadth is one-fourth their length. With them minute granular particles are seen in the cells. They occur in greatest numbers in the cells of the upper layers of the true skin, which are considerably swollen by their presence. They never penetrate the epithelial layer, nor are they found in epithelial cells in any position. When the protoplasm of the cell is interfered with by the later tissue-changes of the disease, the bacillus perishes. They are found not only in the leprous cells, but also in those of the connective tissue running between the agglomerated masses of the former. Between the leprous cells and the filaments of connective tissue but few free bacilli are seen. The neoplasms of the mucous membrane and of many organs of the body have been found to contain them also. In the blood they have been detected by some observers. Their presence in the nerve-tissues is of importance as throwing light upon the question of the specific or inflammatory nature of the morbid processes above described as affecting them. If we regard the bacteria as pathognomonic of leprous tissue-changes, their occurrence, recognized in the cells penetrating between the fibres of the peripheral nerves, would seem to make all primary structural changes identical, and the anæsthetic as much as the tubercular form the direct result of their presence. Neisser draws the following conclusions from his investigations: "Leprosy is a real bacterial disease, caused by a special kind of bacterium. The bacilli appear in the tissues as such, or more probably as spores, and remain for a longer or shorter time in a state of incubation, according to circumstances, in dépôts, perhaps in the lymph-glands. This period, much longer than in other infective diseases, is in proportion to the physiological resistance of the human organism compared with the feeble developing power of the bacilli. It, as well as the course of the disease, is more rapid in tropical countries than in Europe. From these dépôts the disease extends throughout the body in those portions of the skin most exposed, the face, hands, elbows, knees, and into the peripheral nerves. The other organs are less freely invaded. The bacilli excite inflammation, and by a specific action transform the migrating cell into the leprous cell. Leprosy is probably an infectious disease, and its specific products are contagious—viz. the leprous cells of the tubercles, the tissue-fluids, and the pus containing bacilli or viable spores. On the other hand, the pus may not always be infectious, as the fluid contained in the bullæ is not."

It must be said that the bacterial nature of leprosy, if established in accordance with the above observations, furnishes a satisfactory basis of explanation of all facts, historical, clinical, and pathological, which have so long been awaiting solution. The inability of the parasite to penetrate the epithelial layer of the skin and mucous membrane explains why contagion is so difficult, and why the ulcerative tubercular form would be more favorable to such transference than the anæsthetic variety.

DIAGNOSIS.—Leprosy in some of its early appearances may be readily confounded with vitiligo, morphoea, pemphigus, lupus, and syphilis. In some cases its prodromal manifestations cannot be positively diagnosticated until other symptoms have developed, which by concurrence establish their true significance. Such are the pemphigus-like bullæ, the pigment-changes, and the smaller tubercular efflorescences. In regions where the disease occurs only by importation, and in the so-called sporadic cases, it is not at all strange that it should fail of recognition, even in well-advanced forms, unless the observer is acquainted with its whole symptomatology. On the other hand, there is no disease which presents more strikingly characteristic features in its advanced stages.

PROGNOSIS.—Leprosy is almost uniformly a fatal affection, and its course toward this termination varies but slightly under the most diverse conditions of life. Its development and progress are naturally more rapid under circumstances of least individual resistance, where food is poor and scanty, where extremes of climate are most felt, where the constitution of the individual or nation is debilitated by previous disease, as that of the Hawaiians by syphilis, or where no proper professional care is employed. It has been believed that a change of residence from infected to non-leprous regions would retard its advance or avert its appearance in those supposed to be hereditarily disposed; but the former effect follows probably only so far as the general condition of the patient is affected by the change, as in other constitutional disorders, and the latter is necessarily a matter wholly of conjecture. No case of leprosy in the Norwegian colony in our North-western States has ceased to progress after arrival toward its fatal ending, even if this has been somewhat delayed in individual cases under more generous ways of living. If it could be known that a child born in Norway had escaped leprosy by removal to America, we should not, if we accept the bacterial origin of the disease, consider that climate or other mysterious influences had overcome its inherited tendencies, but that it had been taken away from the chance of direct inoculation. It is stated that very rarely cases cease to progress beyond certain stages even in countries where the disease is endemic. The course, as has been stated, varies according to the clinical form, the duration of the tubercular variety being on an average but one-half that of the purely anæsthetic type. Leprosy may be called the slow disease, its period of incubation, so far as this can be determined, extending from one to several years, its prodromal stage lasting often several more years, and its well-developed forms requiring at times more than twenty years to destroy the patient. Cases sometimes prove fatal, however, in a single year.

TREATMENT.—In a disease which affects so many of the races and such great numbers of mankind, which has been for centuries the object of special attention on the part of physicians, and of late years of government commissions and of eminent pathologists, it is evident that every remedy which the materia medica includes, as well as those of merely popular reputation in the widely-diverse geographical regions in which it prevails, must have been employed in its treatment. None of them exert any specific action upon it; it remains incurable. Every year some new article is employed with the usual claims of success which accompany the introduction of new remedies, but they merely swell the long list of failures in the therapeutics of the affection. Still, leprosy is influenced somewhat by medical care; life may be prolonged and made more comfortable. To this end we may employ remedies which are capable of improving and maintaining the constitutional powers of resistance to the disease, such as are found of service in other chronic wasting affections. The patient is to be put in as healthy ways of living as possible, removed from debilitating localities, and given generous diet and tonics, as iron and quinia. Several new drugs which seem to stimulate the nutrition and produce temporary improvement in the local and general symptoms have lately been widely employed, as Gurjun balsam and chaulmoogra oil, but they have wrought no cure. Digestion is to be aided, diarrhoea to be checked, and disturbances of respiration to be alleviated. Local treatment is also of service. The tubercles may sometimes be made to disappear—partly, at least—by stimulating applications, and ulcers made to heal by cauterization and other well-known methods of dressing. These ulcers and their secretions should be regarded as possible sources of infection by attendants and members of the patient's household. For the anæsthetic alterations in the tissues but little can be done locally. If the bacterial origin and causation of the disease be eventually established, its future extinction must be based upon studies directed to the nature and mode of protection against this organism. Collectively, the disease should be treated by every nation by thorough segregation, and importation should be prevented by the most rigid quarantine laws.