{89} Having now explained the mechanism of the two forms of jaundice--that arising from suppression, and that induced by obstruction--it only remains for me to remind my readers, that there is frequently a combination of the two conditions. Jaundice from obstruction, for example, cannot long exist without becoming complicated with jaundice from suppression. The continued backward pressure exerted on the hepatic parenchyma by the over-distended bile-tubes, sooner or later impedes the circulation in the organ to an extent sufficient to induce an impairment, if not an almost total arrest of the biliary secretion. Hence it is, that in the last stage of jaundice from obstruction, the biliary acids gradually diminish, and at last finally disappear from the urine. We have it, nevertheless, in our power to distinguish between the two forms of disease--for whereas, in jaundice arising from simple suppression, there is only an absence of the bile-acids; in jaundice from obstruction, complicated with suppression, the absence of the bile-acids is usually associated with the presence of tyrosine, and leucine. For before complete suppression occurs as a result of obstruction, the hepatic tissue has already had its nutrition so impaired, as to admit of the formation of these foreign substances. Lastly, the history of the case will of itself be an important guide. {90} EPIDEMIC JAUNDICE. It is seldom that jaundice attacks persons in an epidemic form; as it does so occasionally, however, and that too in almost all countries, it is necessary that I should say a few words on its pathology. In a quotation, in the "Medical Times and Gazette," from the "Recueil de Mémoires de Médecine Militaire," vol. iii. p. 374, it is stated that, "M. Martin gave an account of an epidemic of jaundice which he had the opportunity of observing among the artillery and engineers of the French army stationed at Pavia during the Italian war. It commenced during the great heats of August, and terminated by the end of October. There occurred 71 cases in an effective of 1022 men. The causes he considers to have been the unusual heat, which gave rise to great congestion of the liver, the fatigue of long marches (the mounted men suffering oftener in proportion than the unmounted), indulgence in alcoholic drinks, and marsh miasmata. Great increase in the size of the liver in most of the cases, and of the spleen in many, was observed, and all complained of pain in the epigastrium and in the hypochondria. In fact, this last was the first symptom of the approaching jaundice. None of the cases proved fatal. Professor San-Galli {91} informed M. Martin that a similar epidemic prevailed in the town of Pavia at the same time."