Enough has now been said to indicate that disease originates as a reaction between the cause of it and the body. Withhold food, and starvation--the disease--follows. Withhold fresh air and oxygen, and the tissue breaks down; disease results as a reaction from the normal use of air and the demands of the body for oxygen. Allow bacteria admission to the body and settlement in the tissues or organs most agreeable to each particular one, and these will grow, multiply, and, unless overcome by the natural resistance of the body, will conquer and destroy, causing sooner or later death and decay. =Immunity Sought by Inoculation.=--Many diseases that now yield to no curative treatment are being met by inoculation. By this method the body is reinforced by serum injections, that disease germs and infections may be warded off, or in case of attack, be so fortified against the disease germs as to destroy them or render them inactive. =Some Animals More Resistant to Disease.=--An infectious and contagious disease may affect a herd or flock, destroying few or many. Some may never be affected and yet be subjected to exposure and contagion; such are immune and resist this particular disease. Others may suffer a mild attack, but throw it off with no disastrous consequence; such are strong and their organs ably fortified against any injurious inroad by the disease. On the other hand the majority in a flock or herd is not so able to throw off the disease for the reason of being predisposed by nature to such attacks; their very susceptibility invites attack, and if the infection is intensely virulent the affected body will most likely yield and death follow. THE COURSE OF DISEASE Each disease possesses its own peculiar characteristics, which are more or less conspicuous in each individual case. Then, too, some diseases develop quickly and end quickly. Others run a course of several weeks; and still others several months or even years. The first class is acute, the second chronic. In both kinds nature is at work endeavoring always to effect a cure; and, unless other complications arise, the result of improper food, bad sanitary quarters, bad air, or conditions not conducive to health, recovery will, in most cases, result. The great drawback to rapid recovery comes from the outside influences that counteract the curative processes of the body itself. Good nursing, good air, proper food, are back of rapid recovery.