The condition of the skin is a fair index to the condition of the animal. The effect of disease and emaciation upon the pliability of the skin have been referred to above. There is no part of the body that loses its elasticity and tone as a result of disease sooner than the skin. The practical herdsman or flockmaster can gain a great deal of information as to the condition, of an animal merely by grasping the coat and looking at and feeling the skin. Similarly, the condition of the animal is shown to a certain extent by the appearance of the mucous membranes. For example, when the horse is anemic as a result of disease or of inappropriate feed the mucous membranes become pale. This change in the mucous membranes can be seen most readily in the lining of the eyelids and in the lining of the nostril. For convenience of examination the eyelids can readily be everted. Paleness means weak circulation or poor blood. Increased redness occurs physiologically in painful conditions, excitement, and following severe exertion. Under such conditions the increase of circulation is transitory. In fevers there is an increased redness in the mucous membrane, and this continues so long as the fever lasts. In some diseases red spots or streaks form in the mucous membrane. This usually indicates an infectious disease of considerable severity, and occurs in blood poisoning, purpura hemorrhagica, hemorrhagic septicemia, and in urticaria. When the liver is deranged and does not operate, or when the red-blood corpuscles are broken down, as in serious cases of influenza, there is a yellowish discoloration of the mucous membrane. The mucous membranes become bluish or blue when the blood is imperfectly oxidized and contains an excess of carbon dioxid. This condition exists in any serious disease of the respiratory tract, as pneumonia, and in heart failure. The temperature of the skin varies with the temperature of the body. If there is fever the temperature of the skin is likely to be increased. Sometimes, however, as a result of poor circulation and irregular distribution of the blood, the body may be warmer than normal, while the extremities (the legs and ears) may be cold. Where the general surface of the body becomes cold it is evident that the small blood vessels in the skin have contracted and are keeping the blood away, as during a chill, or that the heart is weak and is unable to pump the blood to the surface, and that the animal is on the verge of collapse.