When taken from the thoracic duct, a few hours after a meal, when, probably, the chylous element prevails, it is whitish, opaque, liquid, like milk, with generally a reddish shade; a short time after separation from the body, it coagulates; the clot is at first pale, but it soon becomes light crimson red; the milkiness of the serum is due to the presence of oil; it contains albumen, and coagulates by heat; except that it is more dilute, and that the hematosine is for the most part absent, the chyle and lymph have the same composition as the blood. It appears to vary, however, with the nature of the food, as Dr. Prout found the chyle of persons fed on vegetables to contain a much smaller quantity of albumen than when they had had animal food. Dr. Prout also indicates in chyle the presence of a substance which he terms incipient albumen, which is not coagulated by heat, except after the addition of acetic acid; the properties of this form of albumen, however, are not fully known. _Constitution of the Urine in Health and Disease._—The nature of this secretion has at all times been an object of considerable interest to the chemist, from the indications which changes in its composition give of diseases of important organs and from the number and interest of the different organic substances it contains. As in almost all other branches of animal chemistry, Burzelius first determined its composition, and lately Lecaner has ascertained with great care the limits to which the proportions of its ingredients may vary in health, and this established a correct basis of comparison for urine in the various conditions of diseases. _Of the Urine in Disease and after Death—Urinary Calculi._—To the chemist, the indications of disease of the urinary and digestive organs, formed by changes in the composition of urine, are most valuable. The majority of the substances which are taken into the circulation, but are incapable of assimilation to our organs, are thrown off by this secretion, and hence a variety of medicinal substances may be traced to it after having been ingested, sometimes quite unaltered, at others modified in their natures. Thus if alkaline salts of organic acids be taken into the stomach, the organic material is oxidized, probably during the action of respiration, while the alkali passes into the urine in the state of carbonate. If, however, the organic acid be taken uncombined, it escapes decomposition, and, passing into the urine, produces an abundant precipitate of salts of lime. In the case of the tartaric acid and oxalic acids, some organic bodies, as aspharagine and the oil of turpentine, are decomposed, and the products which they form are execreted, giving to the urine peculiar odors; in the latter case like that of violets. The majority of coloring matters are thrown out of the system by this secretion, while others are not so given off.