Even with a knowledge of all these facts, however, it often baffles the skill, and acumen of the ablest physicians to discover the cause of jaundice. Every now and then cases are met with, where the patient tells us that the jaundice has gradually come on without any assignable cause, and where, after the most careful examination of his history, as well as of his physical condition, we fail to detect a clue to the diagnosis. Cases of this kind are far from uncommon, and this is the more to be regretted, seeing that unless we have a clear appreciation of the cause, it is not only difficult, but even dangerous to treat the symptom. The injudicious administration of {50} a remedy here, may hasten the termination we most desire to retard. The truth of this remark will, however, be better appreciated when I come to consider the rationale of the treatment of jaundice. Meanwhile, it may be advisable to point out a method capable of yielding most important information, when all the ordinary means of diagnosis fail. I allude to the chemistry of the excretions. Although the pathological chemistry of the excretions is as yet in its infancy, it has already given the scientific physician a key to the detection of several diseases, and I trust to be able to show, that even in the obscure cases of jaundice above alluded to, it not only gives us a clue to their cause, but presents us with a guide to their treatment. In jaundice arising from obstruction, the pipe-clay stools are, as in the case of jaundice from suppression, entirely due to the absence of bile from the intestinal canal. The yellowness of the skin is in like manner caused by the accumulation of the bile pigment in the blood, from whence it exudes, and stains the tissues; and, lastly, the saffron-coloured urine results in a similar way from the elimination of the pigment from the blood by the kidneys. Instead, however, of these three conditions arising, as in the case of jaundice from suppression, from the arrest of the biliary functions {51} allowing certain of the constituents of the bile to accumulate in the circulation, they are, in the first place, the result of the re-absorption of the secreted bile from the distended ducts, and gall-bladder. So that while in jaundice from suppression, only those biliary products which exist pre-formed in the blood accumulate in the circulation, in cases of jaundice from obstruction, the biliary products which are manufactured in the liver, equally with those which are pre-formed in the blood, find their way back into the circulation, to be from thence eliminated with the excretions. If then, we could ascertain the presence or absence of these products in the excretions, we should be enabled to distinguish between jaundice resulting from suppression, and jaundice arising from obstruction. Let us now see what the chemistry of the excretions teaches us; and to begin, we shall take the intestinal excretion.