404 PATHOLOGY malarial fever of the American Civil War, and of Rome, Naples, and other localities, is also an excrementitious infection is not so clear. The ordinary typhoid is peculiarly bound up with the modern system of water-closets and sewers, and with the faulty construc tion of the same ; it was a familiar observation in Edinburgh that the Old Town, with its closes and huge tenement-houses, without the water-closet system, remained practically free from typhoid for many years after the disease began to be common in the New Town. The association with faulty sewerage is, however, not an invariable one. The disease occurs among remote and primitive communities, such as Norfolk Island in the Pacific, in Fiji, in Greenland, and elsewhere. According to the contention of Murchison, and of many other living authorities, typhoid fever may, and often does, develop dc novo in an individual who has received, either by the breath or in his food or drink, some peculiar or not altogether ordinary product of focal decomposition. It is not alleged by this school that faecal decomposition under ordinary circumstances (especially under the free access of air) is attended with the risk of typhoid fever ; but that a virulent property may, and often does, develop under some peculiar concurrence of circumstances, especially when faecal matters percolate and accumulate where little air reaches. If the process of typhoid fever be so induced in an isolated case, the de jecta of the patient are specifically virulent ; and from one such case many may be poisoned by means of specifically tainted water or milk distributed in common. The possibility of a dc novo origin of typhoid fever now and then is vehemently objected to by the more doctrinaire school of pathologists ; according to them there is always a pre-existing case, the virus of typhoid having been continuously reproduced ab ceterno. The Exanthemata. Another class of acute infections is those which are virtually independent of external circumstances, which affect all classes equally, and which pass by direct contact from the sick to the sound. The chief diseases of this class are small- Small- pox, measles, and scarlet fever. As to smallpox, it has been con- pox, tended, on the historical and geographical evidence, that it is primarily an African and Indian skin-disease which has acquired spreading power ; and there is really no rival hypothesis of its Measles origin. For measles the evolutional clue would appear to be en tirely lost. The old notion about it, expressed in the name " mor- billi," was that it corresponded to a lesser kind of smallpox. There can be no doubt, however, of its present absolute nosological distinctness. It is as universal in its distribution as smallpox, sparing no race, and, like smallpox, committing its greatest ravages among virgin communities and among the dark-skinned. Scarlet The natural history of scarlet fever is altogether different. It is fever. peculiarly a disease of northern Europe ; it is practically unknown as an epidemic throughout the whole continent of Asia (except Asia Minor), and the whole of Africa (except Algiers) ; and in North and South America and Australasia it seems to have fol lowed the European immigration. One of the most remarkable facts concerning it is that it may occur in quite sporadic or isolated cases in extra- European countries. Some favourable concurrence of circumstances had given it a permanent hold in Europe, or had enabled an occasional erythema of the skin, with fever, to develop into a species of disease, in which the almost diphtheritic affection of the throat, the brawny swelling of the neck (with tendency to sloughing), and the acute affection of the kidneys may be so pro nounced in certain individuals, and in all the cases of certain epidemics, or of the epidemics of certain localities, that the simple type of disease is obscured and the line of evolution lost. Perhaps one clue to the development of scarlatina from non-specific states of the body may be found in the cases of scarlet rash in children, in the surgical wards of hospitals. The evidence seems to show that in such cases there is something different from a merely heightened predisposition to the specific scarlatinal poison, on the supposition that the latter is ubiquitous ; that there is, in fact, an inherent liability in some children to develop a scarlet rash, with fever, near a wound or sore, the condition so developed becoming communicable to others, as in the analogous case of erysipelas. Syphilis. Chronic Infective Diseases. The greatest of the chronic infections is syphilis, unless, indeed, we admit tubercle unreservedly into the same class. Its enormous prevalence in modern times dates, with out doubt, from the European libertinism of the latter part of the 15th century. It is almost certain that the same disease, with symptoms of constitutional infection, had developed in various parts of the ancient world under similar circumstances ; but it is not less certain that a great redevelopment came in about the year 1490 in France, Italy, and Spain, so that we do not even require to assume a continuity of the virus from earlier times. The his torical evidence may be read, in a convenient abridgment, in the third volume of H;iser s Gcschichte der Mcdicin und dcr cpidcrnischcn Krankheiten. Two forms of sore are described concurrently in all writings upon syphilis, and, although it has been usual during the last thirty years to regard only one of these as truly syphilitic, there has always been a certain inability in the profession at large to apprehend the reason for making a radical distinction. One of the forms is a considerable and quickly-developed ulceration, sometimes multiple and with a marked tendency to extend its borders ; it heals under treatment, like any other ulcer, and in many cases there arc no after-effects throughout the body generally. The same person may develop such sores repeatedly. For a considerable time after the establish ment of the doctrine of " true " or indurated infecting sore it was taught that these simple ulcers were never followed by constitu tional infection ; but it is now very generally admitted that ;-iu-h teaching is too rigid or dogmatic, not according with the facts of experience. A recent writer on the subject in Berlin, who has kept records of his private practice, estimates that no fewer than 40 per cent, of all the cases which developed constitutional symptoms were consequent on primary ulcerations that would not have been included in the definition of " true " or Hunterian sores. It is not seriously disputed that these simpler ulcerations may arise inde pendently of conveyance, as the direct results of gross personal negligence. It is at the same time admitted that they may become inveterate, that the process of healing may become irregular, and that they may gradually acquire that character of " induration " which is distinctive of the "true" sore. The various circum stances under which this change of type or development of char acters may take place have, for obvious reasons, escaped being recorded with scientific accuracy ; but of the fact of some such evolution there can be hardly any doubt. The "true" or Hunterian sore is usually at first a small indurated papule, which breaks after a time, but causes little trouble in heal ing. The after-effects are, in their severity and long-continuance, in striking contrast to the disease at the outset. This form of the disease is an affair of infection from beginning to end, from the primary papule to the "gummatous" internal nodules years after ; there is no evolution in the individual of an infective virus out of a common and unclean ulceration. The simple sore, the result of common inflammation under circumstances of gross per sonal negligence is not without a degree of infectiveness of its own. It has a tendency to spread, to enlarge its borders by including the margin of sound tissue in the ulcerative process, and it has also a tendency to infect the nearest packet of lymphatic glands with a suppurative action. Further, it is highly communicable to the persons of others by contact, reproducing one or more sores very like itself, and such communication is accountable for its wide distribution. But that degree of infectiveness is a very dif ferent thing from the true and full syphilitic infection. The latter is often an affair of years, and, it may be, of a lifetime, and it passes directly to the offspring. Its earlier constitutional manifestations are in the throat, the skin, and the hair ; its later in the bones, some muscular structures and some of the viscera, and more particularly in their blood-vessels, or in the blood-vessels of their coverings. It infects the lymphatic glands with an indura- tive rather than a suppurative process, and not only the nearest packet of them but also the lymph -glands in the neck and else where. In seeking for the beginnings of this profound constitutional taint, for the first steps in the evolution of the infection out of a common morbid state of the body, we naturally arrive at that irregular process of healing, or the inveterate soreness which the granulations of a simple ulcer (due to personal unclean ness or con tact with the same) sometimes assume. The tissue of syphilitic formations, wheresoever occurring, has been named by V ire-how "granuloma," being a persistent state of granulation -like tissue, not proceeding to ordinary cicatrization, but to indurative and degenerative changes. In true syphilis,, as we have said, this kind of formation is from first to last the product of an infective virus, equally the primary hard papule, the indurated lymph-glands, the thickening and destruction of mucous surfaces, the nodes and inflammatory products in the periosteum, and the guminata in and upon the viscera. But the type of all this mimetic formative action must have been somewhere acquired or evolved ; and we shall prob ably not err if we seek for the acquisition of the granulomatoua type in the inveteracy and irregular healing of the granulations of an ordinary foul sore under the peculiar circumstances of its own degree of local infectiveness, and in the continuous reproduction of such sores. In this way we should have granulations becoming specifically infective towards the body, or its distant parts, just as the products of simple acute inflammation may be infective to a distance, or as rnelanotic and other slight primary tumours are apt to propagate their texture and characters far and wide, or even as a common granulating sore under certain circumstances of irritation may develop the characters of tumour-tissue and a high degree of tumour-infectiveness. The products of syphilis have a near affinity to new growths of the tumour kind ; and it is with justice that Yirchow includes them among tumours as one of the gramilomata, and Klebs makes provision for them, along with tubercle, glanders, lupus, &c., in a class of "infective tumours." If we take the primary type to be the granulation-tissue of repair we shall assign it an intermediate position, and, at the same time, do justice to the circumstances in which this infective granulation-like new growth
