We have in our bodies a system of canals called arteries and veins, having their head at the heart, which is the main pump that keeps the blood in motion. The arterial circulation consists of those channels which convey the blood--supposed pure blood--away from the heart to the different parts of the body, loaded with the life-giving principle of sustenance, invigoration and heat, while the veins or venous circulation conveys to the heart and lungs the impure blood, loaded many times with disease-breeding germs. Now, in the blood, as it courses through our bodies, are myriads of little vessels called corpuscles; these are what give the blood a red color. There are also a smaller number of white corpuscles, that are known as phagocytes, whose mission is to destroy micro-organisms that are prejudicial to life. In order that you may know their use, I, for convenience sake and to make my meaning better understood, will call them little war vessels, loaded with soldiers, and the soldiers have in their vessels a furnace whose fire never goes out. These vessels and their little warriors are continually sailing through our bodies, hunting for germs of disease, that they catch and throw into their furnace and burn them up. Now, suppose we take a violent cold, thus closing the pores of the skin, and that at the same time the colon is engorged, two of the most important outlets for the filth and decayed matter of our bodies are closed up--for the life of our bodies is one continual process of building anew and tearing down; these two most important sewers are now closed. These little vessels now have their hands full, catching disease-bearing germs that nature cannot throw out through the colon or pores of the skin--both being closed--and we call this condition of things fever. The white corpuscle has but two dumping places now, the lungs or kidneys. Suppose that in the colon is the tubercular ulcer, breeding the bacillus of consumption, and they are absorbed into the circulation. Ordinarily the white corpuscles would be able to destroy them, but now they are so overworked that the tubercular germ lands in the lung tissue alive and well, ready to commence his work of destruction and death. The person developes a hacking cough, and finally goes to the doctor, and he, if he knows his business, probably finds tuberculosis well established. Typhoid fever has its nursery solely in the colon, and gets possession of the citadel of life in the same way as any other germ or contagious disease. What a terrible battle there must be going on in us between our life-preservers and the germs of disease.