_Symptoms and results._ If on a mucous membrane or white skin the color becomes dark red, or violet (cyanotic) with evident distension of the capillaries and veins, the latter of which may stand out as knots or cords, there is an appearance of swelling or enlargement and sometimes coldness of the part. Soon the watery part of the blood transudes in excess, constituting dropsy, with increased swelling and pitting on pressure. On the mucous surfaces it determines an abundant serous secretion. The color is deepened by the escape from the vessels of red globules as well as white. The transudation contains little albumen and only exceptionally fibrine. In connection with the marked deoxidation and high carbonization of the blood, the nutrition of the part is largely arrested together with the functions, secretory, motor or otherwise. The imperfectly nourished vessels may give way, leading to hæmorrhage, or nutrition may be definitely arrested producing moist gangrene or ulceration. Sometimes a thrombus is formed in a congested vein. The changes in the affected organs depend much on the degree and duration of the hyperæmia. If slight and lasting it causes permanent induration and thickening, from connective tissue hyperplasia as frequently seen in the hind limbs of the horse. In case of blood transudations the altered coloring matter gives the various shades of gray, brown or black. If long continued the organ may shrink and atrophy occur from defective nutrition and contraction of the fibrous hyperplasia. In making post mortem examinations mistakes may be made through the occurrence of changes after death. Thus a hvperæmia which was quite considerable during life may virtually disappear through the contraction of the arterial and capillary coats forcing the blood on into the veins. A minute point of extravasation here and there may be the only macroscopic lesion left. Again a marked venous and capillary hvperæmia in a dependent part of the body or of an organ may be entirely due to hypostatic conditions, the blood having settled into the lowest part of the vessels since the death of the animal. To avoid this source of error one must always carefully note the position of the carcass after death. Under other circumstances the superficial veins and capillaries may fill up with blood through the occurrence of decomposition and the evolution of gases in the internal cavities, which empty the splanchnic and parietal vessels by compression.