ANALYSIS OF THE INTESTINAL EXCRETION AS AN AID TO THE DIAGNOSIS OF OBSCURE CASES OF JAUNDICE. The intestinal excretion, in the natural state, consists, firstly,--of those portions of our food which have resisted the action of the digestive juices; secondly,--of the excess of the modified food remaining unabsorbed; and, thirdly,--of the excess, {52} as well as of the effete portions of the digestive secretions themselves. Consequently, if from any cause the digestive secretions do not act properly, the evacuation immediately becomes abnormal, and we can discover by analysis which of the secretions is at fault. Thus, for example, we know that the saliva acts upon the starchy matters of our food, the gastric juice on the albuminous, the pancreatic on the fatty, and that the biliary secretion so modifies the chyme as to allow of its rapid absorption by the lacteal, and portal vessels. If then, from any cause the elaboration, or excretion of any of these digestive juices be interfered with, more of the particular kind or kinds of food on which it acts, passes unchanged through the intestines. Thus, if the salivary secretion be affected, an unusual amount of unmodified starch is found in the stool. If the gastric juice is defective, more albumen than is normal passes away unchanged, and so on with the others. It is clear then, that an examination of the stools must afford us important information regarding the presence, or absence of the normal secretions. A simple inspection of the stool will sometimes at once tell us whether or not bile is present. If it be present, the stool varies from a pale yellow, to a dark olive-green hue, according to the kind, and quantity of biliary colouring matter present, and {53} the nature of the food. It must not be forgotten however, that unless care be taken, the colour deducible from highly-coloured food may be mistaken for an excess of bile. This remark is still more applicable to medicines, for mercury, bismuth, iron, and some other mineral remedies, give rise to dark evacuations so closely resembling bilious stools in appearance, that the only way to distinguish them, is by chemical analysis; when, the presence of the mineral, together with the absence of the bile pigment, and the biliary acids (which are always to be found in normal evacuations), will at once reveal the true nature of the case. I have seen a mistake of this kind happen, and that too, where a patient labouring under jaundice from obstruction, was thought to be passing the usual amount of bile in his stools, when in reality not a particle of bile pigment was present. The colour was in this case entirely due to the food, and ferruginous remedies. Blood from the stomach or bowels, is also apt to be mistaken for biliary matter, more especially when acted on by the gastric juice, which has the property of turning red blood brown. With these exceptions, the absence of bile from the stool, is usually very easily ascertained. For if the patient