396 PATHOLOGY hours when a paroxysm begins and ends respectively. These normal maxima and minima of the body s heat within a diurnal revolution are probably in their origin an adaptation to the periods of labour and rest, both muscular and digestive ; but the habit is an ingrained one, and it obtains when the ordinary round of work and repose, of waking and sleeping, is departed from. In short, it follows the sun and not the vicissitudes of human occupation. Again, the periodical recurrences of the febrile paroxysm appear to follow the lunar intervals. In the United States an ag^ue is observed which has only a weekly paroxysm ; the quartan of northern latitudes is the bi - weekly interval. Tertian and quotidian agues would not of themselves suggest lunar periodicity, but they are related to the types with obvious lunar intervals. The " critical days " of con tinued fevers, which were closely observed in former times, have been brought with much ingenuity under a law of cosmical period icity. It is observed in climatic fevers that, if there be an interval of one or more weeks in which the paroxysms are in abeyance, the next succeeding paroxysm will occur at its due time, and that various minor indications of constitutional disturbance in the inter val (perhaps neuralgias) will have marked the periods when the full paroxysm should have developed. It is necessary to pass over the changes in the blood and in the secretions which accompany the febrile paroxysm. In ague there is a remarkable production of free pigment traced to the red blood- disks, which accumulates in the spleen, the bone-marrow, and else where. The spleen undergoes also an enlargement, and so does the liver ; these are permanent where the malarial cachexia exists. Malarial The malarial cadwxia, marked by hydrremia and lassitude, occurs cachexia. most frequently in those who reside on a waterlogged soil, and are permanently subject to the difficulties of heat-regulation during their work which an atmosphere saturated with watery vapour entails. In such cases there may be no febrile paroxysms from first to last, but a state of adaptation of the body which is at once a disease and almost an ethnological character. Dyseii- Dysentery. It is universally admitted that the causes which tery. produce intermittent in one man of an exposed part) may produce remittent in another, dysentery in a third, and abscess of the liver in a fourth. The incidence in the form of dysentery is apparently capricious ; we have simply the fact that, in a certain proportion of cases, the shock resolves itself into a profound disorganization of the function of the great intestine, which may pass off in a few days or become chronic. The dysenteric seizure is most frequent where there is extreme atmospheric moisture as well as extreme heat, and where the surface of the body is most directly exposed. The region of the loins is somehow a region of great liability, just as the head is, the turban or pith helmet and the loin-cloth of hot countries being the indications of these liabilities. One important point of difference between dysentery and intermittent and remittent is that the former disease runs its course in one attack, whereas in the latter there is the remarkable habit of repetition. The return of the ague paroxysm is an evidence that the disorder is fundamentally one of the nerve-centres ; it is an instance of the "memory" or " habit " which disordered nerve-mechanisms are peculiarly apt to fall into and to retain. In dysentery the disorder is localized ; it is not so much central as peripheral. Whoever has had dysentery once is apt to have it again, and it may become chronic from the first seizure. But it has obvious points of difference from climatic fever, and these differences are associated with the localized inci dence of the primary disturbance. Dysentery may arise under other circumstances than exposure to tropical heat and moisture and to tropical chill, as in wars and famines, in cold, and amidst privations and overcrowding. In such cases it is correlated rather to typhus fever than to malarial, but it is probable that there is the same kind of primary effect produced through the nervous mechanisms as when the vicissitudes of a tropical climate are the cause. Again, the dysentery of slave-ships (formerly) and of coolie-ships (at present), in tropical waters, would appear to be a mixed effect. The effluvia from dysenteric dejecta (or water contaminated by the dejecta) appear to have the power of exciting, in persons who have not been directly exposed to the causes of dysentery, either dysentery itself or some vicarious infection, such as typhus fever or yellow fever, according to the source of the dejecta, or the kind and degree of putrefaction which they had undergone, or according to racial differences in the exposed persons. This question belongs to another part of the subject. Tropical Tropical Abscess of the Liver. This is intimately associated with abscess dysentery in its causation ; it may be either a primary effect, as it of liver, were, instead of dysentery, or it may be an after-effect of one or more attacks of the latter. The primary effect has been dwelt upon by some, and the after-effect by others (notably W. Biuld), but there is really no antagonism between them. As a primary effect tropical abscess of the liver is closely parallel with tropical dysentery and with malarial fever. It is not the effect of heat by itself, but of chill as the sequel of great exposure to heat. Solar heat is trying to the hepatic function, there being an increase of bile ; when the organ has been thus overtaxed it is sensitive to the vicissitudes of heat and cold. It is pointed out by Dr James Johnson ( The Influ ence of Tropical Climates, p. 177) that genuine hepatitis is even more frequent in the Carnatic, with uniform but high temperature, than in Bengal with a more variable and damp climate. "The casual visitor may well wonder how cold can be often applied on the burning coast of Coromandel, where the temperature is high and steady by day, where the nights are, for months together, hot, and seldom raw or damp as at Bombay or Bengal. . . . The European soldier or sailor, exhausted by exercise in the heat of the day and by profuse perspiration, strips himself the moment his duty is over, and throws himself down opposite a window or port to inhale the refreshing sea-breeze, his shirt in all probability dripping with sweat," and the consequences are likely to be an attack of hepatitis or abscess of the liver. A slight abstraction of heat completely upsets the organ which had been most taxed under the particular climate; the incidence is not so much upon the heat -regulating central government as upon a most important member of its executive. As the sudden abstraction of a small amount of heat from a fatigued and perspiring body can produce an extravagant dis charge of heat-producing force, or a paroxysm of fever, by touching the nerve-centre, so it can produce a peripheral effect in the most important of the heat-forming organs, which had under the special circumstances been overtaxed in its function. But the effect on this peripheral part of the heat-producing mechanism is not, for the most part, an increased production of heat as in fever ; it is, in fact, local congestion of blood and suppuration. AVhen the strain falls on the central government the eilect is fever ; when the strain falls on an important member of the executive the effect is inflam mation. Pneumonia. Congestion of the lungs and pneumonia are not Pneu- unfrequent accompaniments of remittent fever in India, especially monia. in those whose health had been previously enfeebled, and among the more ill-clad natives. Pneumonia is liable to occur in those who had been acclimatized to heat, on their exposiire to unusual degrees of cold, as among the negroes in the United States. It has been also observed to become widely prevalent, and in a form which amounted almost to pneumonia pure and simple, among the troops from India employed in Afghanistan in 1838-39, and again in 1878, when they were exposed to the winter cold. Pneumonia is indeed an effect of chill proper to higher lati tudes, just as intermittents and remittents, dysentery, and hepatic abscess are most characteristically the effects of disorder, either central or peripheral, in the heat-regulating mechanism as adapted to tropical and sub-tropical conditions. That pneumonia is nearly always caused by chill is generally believed (the pneumonias of con tagious origin being excepted) ; but it may not be so readily admitted that we have here to deal with a disorder of the heat-regulating mechanism. Pneumonia is, at all events, a fever ; it has an initial period of rigors, more pronounced than in most continued fevers, although far behind the cold fit of intermittent ; the pyrexia is sometimes present for some hours before the other symptoms be come marked ; it usually comes to an end abruptly some time before the consolidation of the lung is all cleared up ; and that crisis in the disease is apt to fall within a week of the onset, and is seldom delayed more than a day or two over the week. The stress of this disease falls upon the lung, usually upon one lung, and more particularly upon the lower half of the lung. Leaving, for the present, the question why the lung is in this case the organ of metabolism upon which the stress falls, let us consider the nature of the pulmonary condition. First, there is engorgement of blood, a condition which is due, according to all analogies, to paralysis of the vase-motor nerves. The abundant capillary vessels round the air-cells are greatly dis tended with blood, and the mucous membrane of all the bronchial tubes is also much injected. Accompanying this state of the pul monary circulation there is more or less obvious distress- 1 of breath ing, or dyspnoea, together with a strong, full, and quickened action of the heart. If the action of the heart be weak and the distress of breathing great it is a sign that the shock has been more severe than the patient, as he is then cir cumstanced, can stand, and death may result merely from congestion of the lung. Usually the extreme congestion of the vessels is relieved by exudation from them into the air-cells which they surround ; if the pa tient should die at this, the second stage of pneumonia, the lung, or lobe of the lung, is found to be solid enough to sink in water ; it is still red, as in the stage of engorge ment, but the cut surface is firm, and under a lens looks to be finely granulated. Each little granule corresponds to an air-cell, ia 65.- Pneumonic lung, stage of rod he- patization; alveoli occupied by fibnnous threads and a few cells.
