After fat has been forced through the lungs and carried to the kidneys it will be eliminated with the urine, and may be found floating upon it in the shape of oil-like drops. Discovery of this condition is positive evidence of fat embolism. It is to be distinguished from shock in that by the time the symptoms of embolic disturbance are at their height, all or nearly all symptoms of pure shock have subsided. Furthermore, cyanosis and embarrassment of respiration are not indicative of shock; and, finally, the discovery of fat in the urine will be corroborative. A mild degree of fat embolism may be noted, if looked for, after almost all serious fractures. It will give rise to slight embarrassment of respiration and cyanosis and to the elimination of fat by the kidneys. =Prognosis.=--Prognosis varies according to the extent of the injury and the proximity of the lesion to the heart and lungs; also to the possibility of continuous entrance of fat, _i. e._, from its continual absorption. Prognosis really depends upon whether the heart can be given sufficient vigor and endurance to continue pumping blood with its burden of fat through the pulmonary circulation. A secondary danger may come from the circulation of this fat-ladened blood through the capillaries of the brain. Should the source of motive power thus become paralyzed with resulting general enfeeblement, death may ensue. When well-marked evidences of fat embolism are present, but are followed by recovery, the worst of the trouble is usually over within forty-eight hours after it begins. =Treatment.=--Obviously treatment is mainly directed toward the heart, so that we may stimulate it to carry its load of fat through from the venous into the arterial system. If it can do this, the fat is disposed of by oxidation or is saponified by the alkalies in the blood. Physiological rest of the injured part is the first indication, however, and if this occurs in a patient, say with delirium tremens, powerful mechanical restraint may be necessary. The most effective cardiac stimulants are called for--alcohol, adrenalin, strychnine. In other respects treatment is largely symptomatic. Next to giving the heart vigor in this way, inhalations of oxygen give the most promise, because of the crying need of the system during this ordeal for this life-giving gas.[1] [1] See paper by the author. New York Medical Journal, August 16, 1884. PHYSICAL PROPERTIES OF THE LEUKOCYTES.