In ancient times derangements of the liver were supposed to be a fundamental condition in nearly all diseases. In the humoral theory of disease, great stress was laid upon the condition of the bile, yellow bile being supposed to produce inflammation, while black bile induced opposite conditions together with hypochondria and insanity. In modern times, the tendency has been to the opposite extreme. When it became thoroughly established that the liver was not the seat of the mind, as was once supposed, and especially when Harvey made the discovery that the heart instead of the liver was the center of the circulation, medical men began to look upon the liver as of far less importance than it had for ages been supposed to be. Even among the common people the liver has come to be regarded as merely an organ for making bile, and it is rare that any diseased condition, besides structural derangements, is attributed to it except such as depend upon some disturbance of secretion. The most recent investigations have shown that the ancient theory was more nearly correct than the modern one, and that while the liver is neither the seat of the mind nor the center of circulation of the blood, it performs at least two other important functions besides that of secreting the bile; namely, elaboration of certain elements of the food, by which process they are fitted to form blood; and the destruction, for the purpose of removal from the system, of worn-out particles which become sources of disease, if retained. The last-named function is independent of the secretion proper, which is both a secretory and an excretory product, being useful in the process of digestion, and at the same time containing poisonous elements which must be eliminated from the system. Thus it will be seen that the function of the liver is an extremely complicated one, and hence it is in the highest degree reasonable to suppose that its functions should be easily deranged and that such derangement should produce a great variety of symptoms. Diseases of the liver, like those of most of the other organs of the body, are chiefly of two classes: functional and structural; that is, those which are chiefly dependent on disturbed action, and those in which the morbid condition of the tissues of the organ is the most prominent condition.

Functional Diseases of the Liver

In the light of modem investigations in pathology, and physiology, there is little reason to doubt but that disordered action of the liver is a morbid condition to which may be attributed a great variety of symptoms which have often been attributed to other organs. The ordinary classification of functional disorders of the liver is as follows: first, diminished secretion; second, increased secretion; third, secretion of morbid bile. As this classification is not in accordance with the most modem views of physiology it must be discarded. In treating this subject we shall follow very closely the classification of Murchison, one of the most recent, and by far the most able writer on diseases of the liver.