It may be added that since these observations were made I have found in the artificially concentrated urine of a case of jaundice from obstruction consequent upon impacted gall-stone, a few balls closely resembling leucine in shape, and size, but differing from it in being excessively dark in colour. No tyrosine crystals were observed, and unfortunately there was not sufficient of the leucine-like substance present in the urine to admit of its being chemically tested. I have thought it my duty to record this fact for the benefit of other observers, as there can be little doubt that we are gradually verging towards some important discovery in a diagnostic point of view. {68} _Melanine in the Urine._ Four years ago (1858), Dr. Eiselt of Prague called attention to the fact that in cases of melanotic cancer of the liver, melanine appears in the renal secretion.[20] When the urine is passed it is usually quite clear; but after standing it becomes of a dark colour, even as dark as porter, without, however, losing its transparency. This deepening of the colour is no doubt due to the oxidation of the melanotic pigment, as the employment of an oxidizing agent, such as nitric or chromic acid, causes the same change to occur instantly. [Footnote 20: Dr. Eiselt states that he also found melanine in the urine in a case of melanotic cancer of the eyeball.] In addition to the cases related by Dr. Eiselt, I am able to add one of considerable importance, as it not only offers a striking illustration of the correctness of his views, but has the double advantage of being an unbiassed record of facts, in consequence of its having been observed, and recorded long before Dr. Eiselt's views were published, and therefore at a time when the author had no idea of its significance. The case occurred about thirteen years ago, in the wards of the Royal Infirmary of Edinburgh. The history of the case I extract from my private note-book. It is briefly as {69} follows:--In the month of May a sailor was admitted into the clinical wards of the Royal Infirmary with symptoms of jaundice from enlarged liver. He stated that he had been a great deal abroad, in hot climates, and admitted that he had been a hard drinker. On admission his skin was of a dusky yellow colour, and had been so since the month of February. The liver was considerably enlarged, and he complained of sudden violent pains in the neighbourhood of the umbilicus. The pain was usually most severe during the night. The urine was of a dark colour, and on the addition of nitric acid, became nearly quite black. It contained no albumen. The patient died ten days after admission. On post-mortem examination, the hepatic duct was found blocked up with malignant deposit, and the liver of a dark green colour. There was also a considerable amount of malignant deposit in the mesentery. This patient, as frequently happens in such cases, became delirious before death.