The toxic effects are chiefly borne by the liver and endothelial linings of the capillaries. The cloudy swelling of the liver cells obstructs the bile canaliculi, causing jaundice, and the more advanced fatty degeneration of these cells brings about disturbances caused by interference with the important liver functions. The degenerative changes in the endothelial cells lining the capillaries bring about the haemorrhages so much a feature of yellow fever. The icterus is apt to be more marked after death, and is especially prominent about the neck and eyelids. Dutroulau considers the absence of icterus in a cadaver as negativing yellow fever. The liver is of a boxwood or chamois skin color and on section is very oily. Haemorrhagic patches may be seen dotting the yellow cut surface. A midzonal fatty degeneration of the liver cells may be noted in cases dying by the 4th and 5th day but later there is degeneration of the entire lobule. The stomach and intestines contain disintegrated blood. Petechiae and erosions are common in the cardiac end of the stomach. The upper part of the duodenum shows changes similar to those seen in the stomach but the other portions of the intestines are essentially negative. The spleen does not show any particular change. The kidneys are enlarged, congested and on microscopical examination show fatty degeneration of the renal epithelium. The adrenals often show fatty degeneration, especially of the cortex. Haemorrhagic infiltrations are marked features in skin and mucous and serous membranes. SYMPTOMATOLOGY =A Typical Case.= _Sthenic Stage._—With very slight or absent prodromata, often during the night, the disease sets in rather abruptly with chilly sensations and the temperature rapidly rises to about 104°F. The face is flushed, dusky and swollen, the eyes injected. Very severe frontal and orbital headaches with marked rachialgia of the lumbo-dorsal region are peculiarly characteristic. The pulse is of high tension and the rate from 90 to 110. The systolic pressure is increased—at times as high as 175. These are the early manifestations of the _first or sthenic period_ of the disease. Vomiting, first of mucus and bile, comes on very early. About the second day albumin appears in the urine and by the 3d or 4th day this is present in large amount and is associated with the presence of hyaline and granular casts. The temperature remains fairly high for three or four days, with morning remissions and evening exacerbations. Of great diagnostic value is _Faget’s law_ as to lack of correlation of temperature and pulse, in that by the 2d day, notwithstanding the high temperature, the pulse rate becomes less and by the 3d or 4th day it has probably decreased 20 to 40 beats from its initial rate.