The annual average of actual admissions of hepatitis in the effective strength of the Madras European army is somewhat more than twenty per cent.; and in the Isle of France and other parts of the same hemisphere, the annual per-centage ranges from eight to eighteen in the effective strength. But the number of cases given in the official returns as inflammation of the liver, forms only a part of the many instances in which the functions and structure of the biliary apparatus are diseased; for there are comparatively few cases of fever and dysentery, and even of diarrhoea and cholera, in which this part of the animal economy is altogether unaffected. Hepatitis, therefore, appears in the returns only when the liver has been the organ affected, or when it has betrayed disorder in a prominent manner. It is well known, however, that in a great many cases which have appeared, and been stated in official returns, as fever, as dysentery, and as chronic diarrhoea, dissection has disclosed most extensive disease in the liver. In some of these cases disorder of this viscus had never been suspected, and in others it had become manifest too late to be remedied. I am disposed to extend this remark to the fevers and dysenteries of the western hemisphere; and I believe that, although the annual average' per-centage of admissions of hepatitis in the effective strength is as low as two per cent. in some of the West Indian colonies, and never above ten per cent., 'as stated in the official returns, averaging altogether as low as four and a half per cent. annually,-disorders of the liver are actually more frequent than those returns make appear, and that those disorders are, in a great measure masked, as in the eastern hemisphere, by concomitant or consequent disease.

But besides those more palpable instances of hepatic disorder, which appear in the official returns as inflammation of the liver, being immediately recognised as such upon their admission into hospital, and in addition to those cases of fever, dysentery, and diarrhoea, wherein the liver has been either in a state of co-existent or consequent disease, there are other instances in which this organ is seriously affected; and yet they seldom come under treatment until more important disease has supervened, either in the liver itself or in some other viscus;-the primary disorder of this organ being productive of the consequent disease, which assumes the prominent features and attracts the whole attention of the practitioner, while, in fact, the primary disorder on which it depends is overlooked, and undiscovered unless when disclosed by dissection.

CHAPTER I.

ON FUNCTIONAL DISORDER OF THE BILIARY ORGANS.

UNDER the head of functional disorder may be embraced all those conditions of the liver and its appendages which depart from the healthy state, and are productive of uneasiness to the patient, and lead to further disease. These conditions, although affecting the quantity and quality of the blood circulating in the liver, and of the fluid secreted by it, are not necessarily allied to morbid structure, although, when neglected or improperly treated, they often terminate in inflammatory states and in alterations of the organization of the organ. Indeed, these latter derangements generally proceed from this source, either immediately upon the first functional disorder, or after repeated or long-continued attacks of it. Amongst the disorders of the biliary organs embraced under this head, most frequently occurring in warm climates, are, increased secretion of bile, congestion of blood in the liver, congestion of bile in the biliary ducts and gall-bladder, and torpid function of the liver itself.

SECT. I.-On Increased Secretion of Bile.

One of the earliest effects of change from a cold or temperate climate to a very warm one, upon the European constitution, 'is an increased secretion of bile. This has been ascribed by Dr. Johnson to a sympathy existing between the hepatic functions and those of the skin, the former being increased when the latter is augmented. That an increase of these functions is generally coexistent, particularly soon after the European has arrived in an intertropical country, cannot be questioned; but, it cannot be readily conceded that the increase of the biliary secretion is so immediately the result of sympathy with the functions of the skin, as this author infers. The sympathy between the skin and the internal viscera generally, I admit; and in the treatment of disease, a knowledge of, and due attention to, the fact, are matters of the very first importance; but I am much more inclined to adopt

another explanation of the phenomenon of increased secretion of bile, which has been assigned to it by other pathologists. It has been ascertained, by the experiments of Crawford, Lavoisier, and Sequin, and of Dr. Prout and Dr. Fyfe, afterwards repeated by Dr. Copland, in a warm climate, that the quantity of carbonic acid gas, formed by respiration in a given time, is much diminished in a high temperature, and under circumstances which lower the powers of life. This being established by numerous experiments, undertaken by individuals entirely unbiassed by previously conceived opinions on the subject, it becomes a basis on which much important speculation respecting the origin of several intertropical disorders may be founded.

If less carbon be evolved from the blood by respiration, in a given time in a warm climate than in a cold one, whilst the quantity of carbonaceous materials conveyed into the circulation is equally great, it must follow, that this substance will soon be greatly in excess, provided that the function of eliminating it from the blood, (which is discharged by the lungs, in a diminished ratio in a warm climate,) is not performed by some other organ. Thus, therefore, there is one of two states to be expected to supervene in Europeans upon their arrival in a warm climate, namely, that owing to the diminished excretion of carbon through the medium of respiration, this substance will be either in excess in the blood, or be eliminated by the vicarious increase of the function of some other organ. But bile is chiefly formed of carbon and hydrogen; therefore, when this secretion is increased, a larger quantity of carbon will be eliminated from the circulating mass, and thus the excess of this substance in the blood will be guarded against. The observations now offered with respect to carbon, may be equally well applied to the quantity of aqueous vapour given off from the blood in the lungs; for, in a high temperature, when the air is already saturated with moisture, a much less quantity of aqueous vapour will accompany the expired air, than in a cold and dry state of the atmosphere; and thus the aqueous part of the blood will be in excess, if it be not excreted in greater abundance by some other part of the animal economy. Hence it is that the fluid excretions of the skin, the secretions of the liver and of the mucous surface of the alimentary canal, become so frequently augmented in warm and moist climates; and when this is the case, a considerable portion of carbon is also evolved from the system, in the state of carbonic acid gas.

From the experiments of the physiologists alluded to, it may be inferred that, owing to the diminished formation of carbonic acid gas in the lungs, during a high temperature of the atmosphere the secretion of bile may be expected to be increased, and the liver may be considered, in a warm climate, as performing an increased office, in proportion as the influence of respiration upon the blood in the lungs is diminished. Thus we have a very important fact in the causation of those disorders which are attended with an increased secretion of bile accounted for, namely, that such disorders increase in frequency and in severity with the rise in temperature, and with the prevalence of those other causes which diminish the changes produced upon the blood by respiration. Dr. Prout and Dr. Fyfe found, that the changes induced upon the blood by respiration are diminished during sleep, by the depressing passions of the mind, by fatigue, by the use of vinous and spirituous liquors, especially when taken upon an empty stomach, by low diet, by mercurial irritation, and by whatever diminishes the powers of life. Dr. Copland, moreover, found that the changes effected by the air in respiration, in those experiments which he performed in a warm climate, were even to a less extent, and furnished much less carbonic acid gas in a given time, than those experiments which he performed in an artificially increased temperature in a cold climate; and this further diminution of the changes effected by respiration upon the atmosphere in a very warm climate he imputed to the presence of malaria, and to the circumstance of more moisture existing in an intertropical atmosphere than in an artificial high temperature in a cold country. The relation subsisting between the temperature of a country and the prevalence of diseases characterised by increased secretion of bile, and disorders of the biliary organs, is thus accounted for.

That increased secretion of bile is evident in all Europeans immediately upon their arrival in India and other warm climates, cannot for a moment be doubted by any who have visited intertropical countries, or who have observed the character of the disorders occurring in temperate or cold regions during seasons of unusual warmth; and it will be as readily conceded, that this increase and disorder of the biliary secretions are in proportion to the elevation of the temperature into which the natives of cold climates are transported. But not only are the disorders experienced by Europeans upon their removal into a warm country, characterised by an exuberant secretion of bile, but the excess of this secretion

generally, in the first instance, is the immediate cause of disorder,all the derangements first experienced arising from this cause, and usually disappearing when it is removed. Of this fact, many cases might be adduced in which diarrhoea, nausea, and general disorder from increased secretion and accumulation of bile have been produced.

These cases constitute some of the slighter forms of disorder resulting from the influence of a warm climate upon Europeans. But it is only one of several modes in which the functions of the biliary organs become deranged; the chief origin of such disorder, in almost every case, being more or less dependent upon the manner in which the function of respiration becomes affected in Europeans, upon their removal into a higher range of temperature than that to which they are adapted by organisation and habit. An increase of the biliary secretions in a warm climate is a necessary consequence of a diminished state of function in the lungs; and, in consequence of such diminution of the changes effected by respiration upon the blood, during considerable elevations of temperature, those materials which should be conveyed from the system by the respired air must soon be in excess, provided that the supply continues undiminished; or, in other words, provided that these materials are carried into the circulation, through the medium of the digestive organs, and owing to the nature of the food, in greater quantity than they are eliminated from it by respiration, unless some other organ supplies, by a vicarious state of its function, the diminished office of the lungs. The organ which takes upon itself this vicarious office, is the liver; and it seems to perform this duty more from the circumstance of those materials whence bile is formed being conveyed to it in the blood in much greater abundance than usual, than from any absolute or primary increase of its vital actions. The abundance of the constituents of the bile conveyed by the circulation to this viscus, seems to facilitate its operations in the formation of this fluid, and to stimulate it to increased action; and if this secretion be not duly discharged from the biliary ducts and gall-bladder, but, either from the state in which it is secreted, or from any other cause, accumulates in these situations, until it acquires properties of an irritating and hurtful tendency, much constitutional disorder may be the result; and this disorder may assume various features, according to the habit and temperament of the patient, and the concurrent circumstances in which it may

supervene.

To illustrate this part of my subject, I shall first offer some